U.S. Supreme Court Diamond v. Chakrabarty, 447
U.S. 303 (1980) Diamond v.
Chakrabarty No. 79-136 Argued March 17, 1980 Decided June 16, 1980 447
U.S. 303 CERTIORARI TO THE UNITED STATES
COURT OF CUSTOMS AND PATENT APPEALS Syllabus Title 35 U.S.C. § 101 provides for the issuance of a patent to a
person who invents or discovers "any" new and useful "manufacture"
or "composition of matter." Respondent filed a patent application
relating to his invention of a human-made, genetically engineered
bacterium capable of breaking down crude oil, a property which is
possessed by no naturally occurring bacteria. A patent examiner's
rejection of the patent application's claims for the new bacteria
was affirmed by the Patent Office Board of Appeals on the ground
that living things are not patentable subject matter under § 101.
The Court of Customs and Patent Appeals reversed, concluding that
the fact that micro-organisms are alive is without legal
significance for purposes of the patent law. Held: A live, human-made micro-organism is patentable
subject matter under § 101. Respondent's micro-organism constitutes
a "manufacture" or "composition of matter" within that statute. Pp. 447 U. S.
308 -318.

															(a) In choosing such expansive terms as "manufacture" and
"composition of matter," modified by the comprehensive "any,"
Congress contemplated that the patent laws should be given wide
scope, and the relevant legislative history also supports a broad
construction. While laws of nature, physical phenomena, and
abstract ideas are not patentable, respondent's claim is not to a
hitherto unknown natural phenomenon, but to a nonnaturally
occurring manufacture or composition of matter -- a product of
human ingenuity "having a distinctive name, character [and] use." Hartranft v. Wiegmann, 121 U. S. 609 , 121 U. S. 615 . Funk Brothers Seed Co. v. Kalo Inoculant Co., 333 U.
S. 127 , distinguished. Pp. 447 U. S.
308 -310.

															(b) The passage of the 1930 Plant Patent Act, which afforded
patent protection to certain asexually reproduced plants, and the
1970 Plant Variety Protection Act, which authorized protection for
certain sexually reproduced plants but excluded bacteria from its
protection, does not evidence congressional understanding that the
terms "manufacture" or "composition of matter" in § 101 do not
include living things. Pp. 447 U. S. 310 -314. Page 447 U. S. 304 (c) Nor does the fact that genetic technology was unforeseen
when Congress enacted § 101 require the conclusion that
micro-organisms cannot qualify as patentable subject matter until
Congress expressly authorizes such protection. The unambiguous
language of § 101 fairly embraces respondent's invention. Arguments
against patentability under § 101, based on potential hazards that
may be generated by genetic research, should be addressed to the
Congress and the Executive, not to the Judiciary. Pp. 447 U. S.
314 -318.

															596 F.2d 952, affirmed.

															BURGER, C J., delivered the opinion of the Court, in which
STEWART, BLACKMUN, REHNQUIST, and STEVENS, JJ., joined. BRENNAN,
J., filed a dissenting opinion, in which WHITE, MARSHALL, and
POWELL, JJ., joined, post, p. 447 U. S.
318 . Page 447 U. S. 305 MR. CHIEF JUSTICE BURGER delivered the opinion of the Court.

															We granted certiorari to determine whether a live, human-made
micro-organism is patentable subject matter under 35 U.S.C. §
101. I In 1972, respondent Chakrabarty, a microbiologist, filed a
patent application, assigned to the General Electric Co. The
application asserted 36 claims related to Chakrabarty's invention
of

															"a bacterium from the genus Pseudomons containing therein at
least two stable energy-generating plasmids, each of said plasmids
providing a separate hydrocarbon degradative pathway. [ Footnote 1 ]"

															This human-made, genetically engineered bacterium is capable of
breaking down multiple components of crude oil. Because of this
property, which is possessed by no naturally occurring bacteria,
Chakrabarty's invention is believed to have significant value for
the treatment of oil spills. [ Footnote 2 ]

															Chakrabarty's patent claims were of three types: first, process
claims for the method of producing the bacteria; Page 447 U. S. 306 second, claims for an inoculum comprised of a carrier material
floating on water, such as straw, and the new bacteria; and third,
claims to the bacteria themselves. The patent examiner allowed the
claims falling into the first two categories, but rejected claims
for the bacteria. His decision rested on two grounds: (1) that
micro-organisms are "products of nature," and (2) that, as living
things, they are not patentable subject matter under 35 U.S.C. §
101.

															Chakrabarty appealed the rejection of these claims to the Patent
Office Board of Appeals, and the Board affirmed the examiner on the
second ground. [ Footnote 3 ]
Relying on the legislative history of the 1930 Plant Patent Act, in
which Congress extended patent protection to certain asexually
reproduced plants, the Board concluded that § 101 was not intended
to cover living things such as these laboratory created
micro-organisms.

															The Court of Customs and Patent Appeals, by a divided vote,
reversed on the authority of its prior decision in In re
Bergy, 563 F.2d 1031, 1038 (1977), which held that "the fact
that micro-organisms . . . are alive . . . [is] without legal
significance" for purposes of the patent law. [ Footnote 4 ] Subsequently, we granted the Acting
Commissioner of Patents and Trademarks' petition for certiorari in Bergy, vacated the judgment, and remanded the case "for
further consideration in light of Parker v. Flook, 437 U. S. 584 (1978)." 438 U.S. 902 (1978). The Court of Customs and Patent
Appeals then vacated its judgment in Chakrabarty and
consolidated the case with Bergy for reconsideration.
After reexamining both cases in the light of our holding in Flook, that court, with one dissent, reaffirmed its
earlier judgments. 596 F.2d 952 (1979). Page 447 U. S. 307 The Commissioner of Patents and Trademarks again sought
certiorari, and we granted the writ as to both Bergy and
Chakrabarty. 444 U.S. 924 (1979). Since then, Bergy has
been dismissed as moot, 444 U.S. 1028 (1980), leaving only Chakrabarty for decision. II The Constitution grants Congress broad power to legislate to

															"promote the Progress of Science and useful Arts, by securing
for limited Times to Authors and Inventors the exclusive Right to
their respective Writings and Discoveries."

															Art. I, § 8, cl. 8. The patent laws promote this progress by
offering inventors exclusive rights for a limited period as an
incentive for their inventiveness and research efforts. Kewanee
Oil Co. v. Bicron Corp., 416 U. S. 470 , 416 U. S.
480 -481 (1974); Universal Oil Co. v. Globe Co., 322 U. S. 471 , 322 U. S. 484 (1944). The authority of Congress is exercised in the hope that

															"[t]he productive effort thereby fostered will have a positive
effect on society through the introduction of new products and
processes of manufacture into the economy, and the emanations by
way of increased employment and better lives for our citizens." Kewanee, supra, at 416 U. S.
480 .

															The question before us in this case is a narrow one of statutory
interpretation requiring us to construe 35 U.S.C. § 101, which
provides:

															"Whoever invents or discovers any new and useful process,
machine, manufacture, or composition of matter, or any new and
useful improvement thereof, may obtain a patent therefor, subject
to the conditions and requirements of this title."

															Specifically, we must determine whether respondent's
micro-organism constitutes a "manufacture" or "composition of
matter" within the meaning of the statute. [ Footnote 5 ] Page 447 U. S. 308 III In cases of statutory construction we begin, of course, with the
language of the statute. Southeastern Community College v.
Davis, 442 U. S. 397 , 442 U. S. 405 (1979). And "unless otherwise defined, words will be interpreted as
taking their ordinary, contemporary, common meaning." Perrin v.
United States, 444 U. S. 37 , 444 U. S. 42 (1979). We have also cautioned that courts "should not read into
the patent laws limitations and conditions which the legislature
has not expressed." United States v. Dubilier Condenser
Corp., 289 U. S. 178 , 289 U. S. 199 (1933) .

															Guided by these canons of construction, this Court has read the
term "manufacture" in § 101 in accordance with its dictionary
definition to mean

															"the production of articles for use from raw or prepared
materials by giving to these materials new forms, qualities,
properties, or combinations, whether by hand labor or by
machinery." American Fruit Growers, Inc. v. Brogdex Co., 283 U. S. 1 , 283 U. S. 11 (1931). Similarly, "composition of matter" has been construed
consistent with its common usage to include

															"all compositions of two or more substances and . . . all
composite articles, whether they be the results of chemical union,
or of mechanical mixture, or whether they be gases, fluids, powders
or solids." Shell Development Co. v. Watson, 149 F.
Supp. 279 , 280 (DC 1957) (citing 1 A. Deller, Walker on Patents
§ 14, p. 55 (1st ed.1937)). In choosing such expansive terms as
"manufacture" and "composition of matter," modified by the
comprehensive "any," Congress plainly contemplated that the patent
laws would be given wide scope.

															The relevant legislative history also supports a broad
construction. The Patent Act of 1793, authored by Thomas Jefferson,
defined statutory subject matter as "any new and useful art,
machine, manufacture, or composition of matter, or any new or
useful improvement [thereof]." Act of Feb. 21, 1793, § 1, 1 Stat.
319. The Act embodied Jefferson's philosophy that "ingenuity should
receive a liberal encouragement." Page 447 U. S. 309 5 Writings of Thomas Jefferson 75-76 (Washington ed. 1871). See Graham v. John Deere Co., 383 U. S.
1 , 383 U. S. 7 -10
(1966). Subsequent patent statutes in 1836, 1870, and 1874 employed
this same broad language. In 1052, when the patent laws were
recodified, Congress replaced the word "art" with "process," but
otherwise left Jefferson's language intact. The Committee Reports
accompanying the 1952 Act inform us that Congress intended
statutory subject matter to "include anything under the sun that is
made by man." S Rep. No 1979, 82d Cong., 2d Sess., 5 (1952);
H.R.Rep. No. 1979, 82d Cong., 2d Sess., 6 (1952). [ Footnote 6 ]

															This is not to suggest that § 101 has no limits, or that it
embraces every discovery. The laws of nature, physical phenomena,
and abstract ideas have been held not patentable. See Parker v.
Flook, 437 U. S. 584 (1978); Gottschalk v. Benson, 409 U. S.
63 , 409 U. S. 67 (1972); Funk Brothers Seed Co. v. Kalo Inoculant Co., 333 U. S. 127 , 333 U. S. 130 (1948); O'Reilly v.
Morse , 15 How. 62, 56 U. S. 112 -121
(1854); Le Roy v.
Tatham , 14 How. 156, 55 U. S. 175 (1853). Thus, a new mineral discovered in the earth or a new plant
found in the wild is not patentable subject matter. Likewise,
Einstein could not patent his celebrated law that E=mc2; nor could
Newton have patented the law of gravity. Such discoveries are
"manifestations of . . . nature, free to all men and reserved
exclusively to none." Funk, supra at 333 U. S.
130 .

															Judged in this light, respondent's micro-organism plainly
qualifies as patentable subject matter. His claim is not to a
hitherto unknown natural phenomenon, but to a nonnaturally
occurring manufacture or composition of matter -- a product of
human ingenuity "having a distinctive name, character [and] Page 447 U. S. 310 use." Hartranft v. Wiegmann, 121 U.
S. 609 , 121 U. S. 615 (1887). The point is underscored dramatically by comparison of the
invention here with that in Funk. There, the patentee had
discovered that there existed in nature certain species of root
nodule bacteria which did not exert a mutually inhibitive effect on
each other. He used that discovery to produce a mixed culture
capable of inoculating the seeds of leguminous plants. Concluding
that the patentee had discovered "only some of the handiwork of
nature," the Court ruled the product nonpatentable:

															"Each of the species of root-nodule bacteria contained in the
package infects the same group of leguminous plants which it always
infected. No species acquires a different use. The combination of
species produces no new bacteria, no change in the six species of
bacteria, and no enlargement of the range of their utility. Each
species has the same effect it always had. The bacteria perform in
their natural way. Their use in combination does not improve in any
way their natural functioning. They serve the ends nature
originally provided, and act quite independently of any effort of
the patentee."

															333 U.S. at 333 U. S. 131 .
Here, by contrast, the patentee has produced a new bacterium with
markedly different characteristics from any found in nature, and
one having the potential for significant utility. His discovery is
not nature's handiwork, but his own; accordingly it is patentable
subject matter under § 101. IV Two contrary arguments are advanced, neither of which we find
persuasive. (A) The petitioner's first argument rests on the enactment of the
1930 Plant Patent Act, which afforded patent protection to certain
asexually reproduced plants, and the 1970 Plant Page 447 U. S. 311 Variety Protection Act, which authorized protection for certain
sexually reproduced plants but excluded bacteria from its
protection. [ Footnote 7 ] In the
petitioner's view, the passage of these Acts evidences
congressional understanding that the terms "manufacture" or
"composition of matter" do not include living things; if they did,
the petitioner argues, neither Act would have been necessary.

															We reject this argument. Prior to 1930, two factors were thought
to remove plants from patent protection. The first was the belief
that plants, even those artificially bred, were products of nature
for purposes of the patent law. This position appears to have
derived from the decision of the Patent Office in Ex parte
Latimer, 1889 Dec.Com.Pat 123, in which a patent claim for
fiber found in the needle of the Pinus australis was rejected. The
Commissioner reasoned that a contrary result would permit "patents
[to] be obtained upon the trees of the forest and the plants of the
earth, which of course would be unreasonable and impossible." Id. at 126. The Latimer case, it seems, came to
"se[t] forth the general stand taken in these matters" that plants
were natural products not subject to patent protection. Thorne,
Relation of Patent Law to Natural Products, 6 J.Pat.Off.Soc. 23,
24 Page 447 U. S. 312 (1923). [ Footnote 8 ] The
second obstacle to patent protection for plants was the fact that
plants were thought not amenable to the "written description"
requirement of the patent law. See 35 U.S.C. § 112.
Because new plants may differ from old only in color or perfume,
differentiation by written description was often impossible. See Hearings on H.R. 11372 before the House Committee on
Patents, 71st Cong., 2d Sess., 7 (1930) (memorandum of Patent
Commissioner Robertson).

															In enacting the Plant Patent Act, Congress addressed both of
these concerns. It explained at length its belief that the work of
the plant breeder "in aid of nature" was patentable invention.
S.Rep. No. 315, 71st Cong., 2d Sess., 8 (1930); H.R.Rep. No. 1129,
71st Cong., 2d Sess., 7-9 (1930). And it relaxed the written
description requirement in favor of "a description . . . as
complete as is reasonably possible." 35 U.S.C. § 162. No Committee
or Member of Congress, however, expressed the broader view, now
urged by the petitioner, that the terms "manufacture" or
"composition of matter" exclude living things. The sole support for
that position in the legislative history of the 1930 Act is found
in the conclusory statement of Secretary of Agriculture Hyde, in a
letter to the Chairmen of the House and Senate Committees
considering the 1930 Act, that "the patent laws . . . at the
present time are understood to cover only inventions or discoveries
in the field of inanimate nature." See S.Rep. No. 315, supra at Appendix A; H.R.Rep. No. 1129, supra at
Appendix A. Secretary Hyde's opinion, however, is not entitled to
controlling weight. His views were solicited on the administration
of the new law. and not on the scope of patentable Page 447 U. S. 313 subject matter -- an area beyond his competence. Moreover, there
is language in the House and Senate Committee Reports suggesting
that, to the extent Congress considered the matter, it found the
Secretary's dichotomy unpersuasive. The Reports observe:

															"There is a clear and logical distinction between the
discovery of a new variety of plant and of certain inanimate
things, such, for example, as a new and useful natural
mineral. The mineral is created wholly by nature unassisted by man.
. . . On the other hand, a plant discovery resulting from
cultivation is unique, isolated, and is not repeated by nature, nor
can it be reproduced by nature unaided by man. . . ."

															S.Rep. No. 315, supra at 6; H.R.Rep. No. 1129, supra at 7 (emphasis added). Congress thus recognized that
the relevant distinction was not between living and inanimate
things, but between products of nature, whether living or not, and
human-made inventions. Here, respondent's micro-organism is the
result of human ingenuity and research. Hence, the passage of the
Plant Patent Act affords the Government no support.

															Nor does the passage of the 1970 Plant Variety Protection Act
support the Government's position. As the Government acknowledges,
sexually reproduced plants were not included under the 1930 Act
because new varieties could not be reproduced true-to-type through
seedlings. Brief for Petitioner 27, n. 31. By 1970, however, it was
generally recognized that true-to-type reproduction was possible,
and that plant patent protection was therefore appropriate. The
1970 Act extended that protection. There is nothing in its language
or history to suggest that it was enacted because § 101 did not
include living things.

															In particular, we find nothing in the exclusion of bacteria from
plant variety protection to support the petitioner's position. See n 7, supra. The legislative history gives no reason for this
exclusion. As the Court of Customs and Page 447 U. S. 314 Patent Appeals suggested, it may simply reflect congressional
agreement with the result reached by that court in deciding In
re Arzberger, 27 C.C.P.A.(Pat.) 1315, 112 F.2d 834 (1940),
which held that bacteria were not plants for the purposes of the
1930 Act. Or it may reflect the fact that, prior to 1970, the
Patent Office had issued patents for bacteria under § 101.
[ Footnote 9 ] In any event,
absent some clear indication that Congress "focused on [the] issues
. . . directly related to the one presently before the Court," SEC v. Sloan, 436 U. S. 103 , 436 U. S.
120 -121 (1978), there is no basis for reading into its
actions an intent to modify the plain meaning of the words found in
§ 101. See TVA v. Hill, 437 U. S. 153 , 437 U. S.
189 -193 (1978); United States v. Price, 361 U. S. 304 , 361 U. S. 313 (1960). (B) The petitioner's second argument is that micro-organisms cannot
qualify as patentable subject matter until Congress expressly
authorizes such protection. His position rests on the fact that
genetic technology was unforeseen when Congress enacted § 101. From
this it is argued that resolution of the patentability of
inventions such as respondent's should be left to Congress. The
legislative process, the petitioner argues, is best equipped to
weigh the competing economic, social, and scientific considerations
involved, and to determine whether living organisms produced by
genetic engineering should receive patent protection. In support of
this position, the petitioner relies on our recent holding in Parker v. Flook, 437 U. S. 584 (1978), and the statement that the judiciary "must proceed
cautiously when . . . asked to extend Page 447 U. S. 315 patent rights into areas wholly unforeseen by Congress." Id. at 437 U. S.
596 .

															It is, of course, correct that Congress, not the courts, must
define the limits of patentability; but it is equally true that,
once Congress has spoken, it is "the province and duty of the
judicial department to say what the law is." Marbury v.
Madison , 1 Cranch 137, 5 U. S. 177 (1803). Congress has performed its constitutional role in defining
patentable subject matter in § 101; we perform ours in construing
the language Congress has employed. In so doing, our obligation is
to take statutes as we find them, guided, if ambiguity appears, by
the legislative history and statutory purpose. Here, we perceive no
ambiguity. The subject matter provisions of the patent law have
been cast in broad terms to fulfill the constitutional and
statutory goal of promoting "the Progress of Science and the useful
Arts" with all that means for the social and economic benefits
envisioned by Jefferson. Broad general language is not necessarily
ambiguous when congressional objectives require broad terms.

															Nothing in Flook is to the contrary. That case applied
our prior precedents to determine that a "claim for an improved
method of calculation, even when tied to a specific end use, is
unpatentable subject matter under § 101." 437 U.S. at 437 U. S. 595 ,
n. 18. The Court carefully scrutinized the claim at issue to
determine whether it was precluded from patent protection under
"the principles underlying the prohibition against patents for ideas' or phenomena of nature." Id. at 437 U. S. 593 .
We have done that here. Flook did not announce a new
principle that inventions in areas not contemplated by Congress
when the patent laws were enacted are unpatentable per
se. To read that concept into Flook would frustrate the
purposes of the patent law. This Court frequently has observed that
a statute is not to be confined to the "particular application[s] .
. . contemplated by the legislators." Barr v. United
States, 324 U. S. 83 , 324 U. S. 90 (1945). Accord, Browder v. United States, 312 U.
S. 335 , 312 U. S. 339 (1941); Puerto Rico v. Shell
Co. , Page 447 U. S. 316 302 U. S. 253 , 302 U. S. 257 (1937). This is especially true in the field of patent law. A rule
that unanticipated inventions are without protection would conflict
with the core concept of the patent law that anticipation
undermines patentability. See Graham v. John Deere Co., 383 U.S. at 383 U. S. 12 -17.
Mr. Justice Douglas reminded that the inventions most benefiting
mankind are those that "push back the frontiers of chemistry.
physics, and the like." Great A. & P. Tea Co. v.
Supermarket Corp., 340 U. S. 147 , 340 U. S. 154 (1950) (concurring opinion). Congress employed broad general
language in drafting § 101 precisely because such inventions are
often unforeseeable. [ Footnote
10 ]

															To buttress his argument, the petitioner, with the support of amicus, points to grave risks that may be generated by
research endeavors such as respondent's. The briefs present a
gruesome parade of horribles. Scientists, among them Nobel
laureates, are quoted suggesting that genetic research may pose a
serious threat to the human race, or, at the very least, that the
dangers are far too substantial to permit such research to proceed
apace at this time. We are told that genetic research and related
technological developments may spread pollution and disease, that
it may result in a loss of genetic diversity, and that its practice
may tend to depreciate the value of human life. These arguments are
forcefully, even passionately, presented; they remind us that, at
times, human ingenuity seems unable to control fully the forces it
creates -- that, with Hamlet, it is sometimes better "to bear those
ills we have than fly to others that we know not of."

															It is argued that this Court should weigh these potential
hazards in considering whether respondent's invention is Page 447 U. S. 317 patentable subject matter under § 101. We disagree. The grant or
denial of patents on micro-organisms is not likely to put an end to
genetic research or to its attendant risks. The large amount of
research that has already occurred when no researcher had sure
knowledge that patent protection would be available suggests that
legislative or judicial fiat as to patentability will not deter the
scientific mind from probing into the unknown any more than Canute
could command the tides. Whether respondent's claims are patentable
may determine whether research efforts are accelerated by the hope
of reward or slowed by want of incentives, but that is all.

															What is more important is that we are without competence to
entertain these arguments -- either to brush them aside as
fantasies generated by fear of the unknown or to act on them. The
choice we are urged to make is a matter of high policy for
resolution within the legislative process after the kind of
investigation, examination, and study that legislative bodies can
provide and courts cannot. That process involves the balancing of
competing values and interests, which, in our democratic system, is
the business of elected representatives. Whatever their validity,
the contentions now pressed on us should be addressed to the
political branches of the Government, the Congress and the
Executive, and not to the courts. [ Footnote 11 ] Page 447 U. S. 318 We have emphasized in the recent past that

															"[o]ur individual appraisal of the wisdom or unwisdom of a
particular [legislative] course . . . is to be put aside in the
process of interpreting a statute." TVA v. Hill, 437 U.S. at 437 U. S. 194 .
Our task, rather, is the narrow one of determining what Congress
meant by the words it used in the statute; once that is done, our
powers are exhausted. Congress is free to amend § 101 so as to
exclude from patent protection organisms produced by genetic
engineering. Cf. 42 U.S.C. § 2181(a), exempting from
patent protection inventions "useful solely in the utilization of
special nuclear material or atomic energy in an atomic weapon." Or
it may choose to craft a statute specifically designed for such
living things. But, until Congress takes such action, this Court
must construe the language of § 101 as it is. The language of that
section fairly embraces respondent's invention.

															Accordingly, the judgment of the Court of Customs and Patent
Appeals is Affirmed. [ Footnote 1 ]

															Plasmids are hereditary units physically separate from the
chromosomes of the cell. In prior research, Chakrabarty and an
associate discovered that plasmids control the oil degradation
abilities of certain bacteria. In particular, the two researchers
discovered plasmids capable of degrading camphor and octane, two
components of crude oil. In the work represented by the patent
application at issue here, Chakrabarty discovered a process by
which four different plasmids, capable of degrading four different
oil components, could be transferred to and maintained stably in a
single Pseudomonas bacterium, which itself has no capacity for
degrading oil.

															[ Footnote 2 ]

															At present, biological control of oil spills requires the use of
a mixture of naturally occurring bacteria, each capable of
degrading one component of the oil complex. In this way, oil is
decomposed into simpler substances which can serve as food for
aquatic life. However, for various reasons, only a portion of any
such mixed culture survives to attack the oil spill. By breaking
down multiple components of oil, Chakrabarty's microorganism
promises more efficient and rapid oil-spill control.

															[ Footnote 3 ]

															The Board concluded that the new bacteria were not "products of
nature," because Pseudomonas bacteria containing two or more
different energy-generating plasmids are not naturally
occurring.

															[ Footnote 4 ] Bergy involved a patent application for a pure culture
of the microorganism Streptomuces vellosus found to be
useful in the production of lincomycin, an antibiotic.

															[ Footnote 5 ]

															This case does not involve the other "conditions and
requirements" of the patent laws, such as novelty and
nonobviousness. 35 U.S.C. §§ 102, 103.

															[ Footnote 6 ]

															This same language was employed by P. J. Federico, a principal
draftsman of the 1952 recodification, in his testimony regarding
that legislation:

															"[U]nder section 101, a person may have invented a machine or a
manufacture, which may include anything under the sun that is made
by man. . . ."

															Hearings on H.R. 3760 before Subcommittee No. 3 of the House
Committee on the Judiciary, 82d Cong., 1st Sess., 37 (1951).

															[ Footnote 7 ]

															The Plant Patent Act of 1930, 35 U.S.C. § 161, provides in
relevant part:

															"Whoever invents or discovers and asexually reproduces any
distinct and new variety of plant, including cultivated sports,
mutants, hybrids, and newly found seedlings, other than a tuber
propagated plant or a plant found in an uncultivated state, may
obtain a patent therefor. . . ."

															The Plant Variety Protection Act of 1970, provides in relevant
part:

															"The breeder of any novel variety of sexually reproduced plant
(other than fungi, bacteria, or first generation hybrids) who has
so reproduced the variety, or his successor in interest, shall be
entitled to plant variety protection therefor. . . ."

															84 Stat. 1547, 7 U.S.C. § 2402(a). See generally 3 A.
Deller, Walker on Patents, ch. IX (2d ed.1964); R. Allyn, The First
Plant Patents (1934).

															[ Footnote 8 ]

															Writing three years after the passage of the 1930 Act, R. Cook,
Editor of the Journal of Heredity, commented:

															"It is a little hard for plant men to understand why [Art. I, §
8] of the Constitution should not have been earlier construed to
include the promotion of the art of plant breeding. The reason for
this is probably to be found in the principle that natural products
are not patentable."

															Florists Exchange and Horticultural Trade World, July 15, 1933,
p. 9.

															[ Footnote 9 ]

															In 1873, the Patent Office granted Louis Pasteur a patent on
"yeast, free from organic germs of disease, as an article of
manufacture." And in 1967 and 1968, immediately prior to the
passage of the Plant Variety Protection Act, that Office granted
two patents which, as the petitioner concedes, state claims for
living micro-organisms. See Reply Brief for Petitioner 3,
and n. 2.

															[ Footnote 10 ]

															Even an abbreviated list of patented inventions underscores the
point: telegraph (Morse, No. 1,647); telephone (Bell, No. 174,465);
electric lamp (Edison, No. 223,898); airplane (the Wrights, No.
821,393); transistor (Bardeen & Brattain, No. 2,524,035);
neutronic reactor (Fermi & Szilard, No. 2,708,656); laser
(Schawlow & Townes, No. 2,929,922). See generally Revolutionary Ideas, Patents & Progress in America, United
States Patent and Trademark Office (1976).

															[ Footnote 11 ]

															We are not to be understood as suggesting that the political
branches have been laggard in the consideration of the problems
related to genetic research and technology. They have already taken
action. In 1976, for example, the National Institutes of Health
released guidelines for NIH-sponsored genetic research which
established conditions under which such research could be
performed. 41 Fed.Reg. 27902. In 1978, those guidelines were
revised and relaxed. 43 Fed.Reg. 60080, 60108, 60134. And
Committees of the Congress have held extensive hearings on these
matters. See, e.g., Hearings on Genetic Engineering before
the Subcommittee on Health of the Senate Committee on Labor and
Public Welfare, 94th Cong., 1st Sess. (1975); Hearings before the
Subcommittee on Science, Technology, and Space of the Senate
Committee on Commerce, Science, and Transportation, 95th Cong., 1st
Sess. (1977); Hearings on H.R. 4759 et al. before the
Subcommittee on Health and the Environment of the House Committee
on Interstate and Foreign Commerce, 95th Cong., 1st Sess.
(1977).

															MR. JUSTICE BRENNAN, with whom MR. JUSTICE WHITE, MR. JUSTICE
MARSHALL, and MR. JUSTICE POWELL join, dissenting.

															I agree with the Court that the question before us is a narrow
one. Neither the future of scientific research, nor even the
ability of respondent Chakrabarty to reap some monopoly profits
from his pioneering work, is at stake. Patents on the processes by
which he has produced and employed the new living organism are not
contested. The only question we need decide is whether Congress,
exercising its authority under Art. I, § 8, of the Constitution,
intended that he be able to secure a monopoly on the living
organism itself, no matter how produced or how used. Because I
believe the Court has misread the applicable legislation, I
dissent. Page 447 U. S. 319 The patent laws attempt to reconcile this Nation's deep-seated
antipathy to monopolies with the need to encourage progress. Deepsouth Packing Co. v. Laitram Corp., 406 U.
S. 518 , 406 U. S.
530 -531 (1972); Graham v. John Deere Co., 383 U. S. 1 , 383 U. S. 7 -10
(1966). Given the complexity and legislative nature of this
delicate task, we must be careful to extend patent protection no
further than Congress has provided. In particular, were there an
absence of legislative direction, the courts should leave to
Congress the decisions whether and how far to extend the patent
privilege into areas where the common understanding has been that
patents are not available. [ Footnote
2/1 ] Cf. Deepsouth Packing Co. v. Laitram Corp.,
supra. In this case, however, we do not confront a complete legislative
vacuum. The sweeping language of the Patent Act of 1793, as
reenacted in 1952, is not the last pronouncement Congress has made
in this area. In 1930, Congress enacted the Plant Patent Act
affording patent protection to developers of certain asexually
reproduced plants. In 1970, Congress enacted the Plant Variety
Protection Act to extend protection to certain new plant varieties
capable of sexual reproduction. Thus, we are not dealing -- as the
Court would have it -- with the routine problem of "unanticipated
inventions." Ante at 447
U.S. 316 . In these two Acts, Congress has addressed the
general problem of patenting animate inventions and has chosen
carefully limited language granting protection to some kinds of
discoveries, but specifically excluding others. These Acts strongly
evidence a congressional limitation that excludes bacteria from
patentability. [ Footnote 2/2 ] Page 447 U. S. 320 First, the Acts evidence Congress' understanding, at least since
1930, that § 101 does not include living organisms. If newly
developed living organisms not naturally occurring had been
patentable under § 101, the plants included in the scope of the
1930 and 1970 Acts could have been patented without new
legislation. Those plants, like the bacteria involved in this case,
were new varieties not naturally occurring. [ Footnote 2/3 ] Although the Court, ante at 447 U. S. 311 ,
rejects this line of argument, it does not explain why the Acts
were necessary unless to correct a preexisting situation. [ Footnote 2/4 ] I cannot share the Court's
implicit assumption that Congress was engaged in either idle
exercises or mere correction of the public record when it enacted
the 1930 and 1970 Acts. And Congress certainly thought it was doing
something significant. The Committee Reports contain expansive
prose about the previously unavailable benefits to be derived from
extending patent protection to plants. [ Footnote 2/5 ] H.R.Rep. Page 447 U. S. 321 No. 91-1605, pp. 1-3 (1970); S.Rep. No. 315, 71st Cong., 2d
Sess., 1-3 (1930). Because Congress thought it had to legislate in
order to make agricultural "human-made inventions" patentable, and
because the legislation Congress enacted is limited, it follows
that Congress never meant to make items outside the scope of the
legislation patentable.

															Second, the 1970 Act clearly indicates that Congress has
included bacteria within the focus of its legislative concern, but
not within the scope of patent protection. Congress specifically
excluded bacteria from the coverage of the 1970 Act. 7 U.S.C. §
2402(a). The Court's attempts to supply explanations for this
explicit exclusion ring hollow. It is true that there is no mention
in the legislative history of the exclusion, but that does not give
us license to invent reasons. The fact is that Congress, assuming
that animate objects as to which it had not specifically legislated
could not be patented, excluded bacteria from the set of patentable
organisms.

															The Court protests that its holding today is dictated by the
broad language of § 101, which cannot "be confined to the particular application[s] . . . contemplated by the
legislators.'" Ante at 447 U. S. 315 ,
quoting Barr v. United States, 324 U. S.
83 , 324 U. S. 90 (1945). But as I have shown, the Court's decision does not follow
the unavoidable implications of the statute. Rather, it extends the
patent system to cover living material Page 447 U. S. 322 even though Congress plainly has legislated in the belief that §
101 does not encompass living organisms. It is the role of
Congress, not this Court, to broaden or narrow the reach of the
patent laws. This is especially true where, as here, the
composition sought to be patented uniquely implicates matters of
public concern.

															[ Footnote 2/1 ]

															I read the Court to admit that the popular conception, even
among advocates of agricultural patents, was that living organisms
were unpatentable. See ante at 447 U. S.
311 -312, and n. 8.

															[ Footnote 2/2 ]

															But even if I agreed with the Court that the 1930 and 1970 Acts
were not dispositive, I would dissent. This case presents even more
cogent reasons than Deepsouth Packing Co. not to extend
the patent monopoly in the face of uncertainty. At the very least,
these Acts are signs of legislative attention to the problems of
patenting living organisms, but they give no affirmative indication
of congressional intent that bacteria be patentable. The caveat of Parker v. Flook, 437 U. S. 584 , 437 U. S. 596 (1978), an admonition to "proceed cautiously when we are asked to
extend patent rights into areas wholly unforeseen by Congress,"
therefore becomes pertinent. I should think the necessity for
caution is that much greater when we are asked to extend patent
rights into areas Congress has foreseen and considered, but has not
resolved.

															[ Footnote 2/3 ]

															The Court refers to the logic employed by Congress in choosing
not to perpetuate the "dichotomy" suggested by Secretary Hyde. Ante at 447 U. S. 313 .
But by this logic, the bacteria at issue here are distinguishable
from a "mineral . . . created wholly by nature" in exactly the same
way as were the new varieties of plants. If a new Act was needed to
provide patent protection for the plants, it was equally necessary
for bacteria. Yet Congress provided for patents on plants, but not
on these bacteria. In short, Congress decided to make only a subset
of animate "human-made inventions," ibid., patentable.

															[ Footnote 2/4 ]

															If the 1930 Act's only purpose were to solve the technical
problem of description referred to by the Court, ante at 447 U. S. 312 ,
most of the Act, and in particular its limitation to asexually
reproduced plants, would have been totally unnecessary.

															[ Footnote 2/5 ]

															Secretary Hyde's letter was not the only explicit indication in
the legislative history of these Acts that Congress was acting on
the assumption that legislation was necessary to make living
organisms patentable. The Senate Judiciary Committee Report on the
1970 Act states the Committee's understanding that patent
protection extended no further than the explicit provisions of
these Acts:

															"Under the patent law, patent protection is limited to those
varieties of plants which reproduce asexually, that is, by such
methods as grafting or budding. No protection is available to those
varieties of plants which reproduce sexually, that is, generally by
seeds."

															S.Rep. No. 91-1246, p. 3 (1970). Similarly, Representative
Poage, speaking for the 1970 Act, after noting the protection
accorded asexually developed plants, stated that, "for plants
produced from seed, there has been no such protection." 116
Cong.Rec. 40295 (1970).


Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co.

OCTOBER TERM, 1996

															Syllabus

															WARNER-JENKINSON CO., INC. v. HILTON DAVIS CHEMICAL
CO.

															CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FEDERAL
CIRCUIT No. 95-728. Argued October 15, 1996-Decided March 3,1997 Petitioner and respondent both manufacture dyes from which
impurities must be removed. Respondent's '''746 patent," which
issued in 1985, discloses an improved purification process
involving the "ultrafiltration" of dye through a porous membrane at
pH levels between 6.0 and 9.0. The inventors so limited their
claim's pH element during patent prosecution after the patent
examiner objected because of a perceived overlap with the earlier
"Booth" patent, which disclosed an ultrafiltration process
operating at a pH above 9.0. In 1986, petitioner developed its own
ultrafiltration process, which operated at a pH level of 5.0.
Respondent sued for infringement of the '746 patent, relying solely
on the "doctrine of equivalents," under which a product or process
that does not literally infringe upon the express terms of a patent
claim may nonetheless be found to infringe if there is
"equivalence" between the elements of the accused product or
process and the claimed elements of the patented invention. Graver Tank & Mfg. Co. v. Linde Air Products
Co., 339 U. S.
605 , 609. Over petitioner's objections that this is an
equitable doctrine and is to be applied by the court, the
equivalence issue was included among those sent to the jury, which
found, inter alia, that petitioner infringed upon the '746
patent. The District Court, among its rulings, entered a permanent
injunction against petitioner. The en banc Federal Circuit
affirmed, holding that the doctrine of equivalents continues to
exist, that the question of equivalence is for the jury to decide,
and that the jury had substantial evidence from which to conclude
that petitioner's process was not substantially different from the
process disclosed in the '746 patent.

															Held:

															(a) In Graver Tank, supra, at 609, the Court, inter
alia, described some of the considerations that go into
applying the doctrine, such as the patent's context, the prior art,
and the particular circumstances of the case, including the purpose
for which an ingredient is used in the patent, the qualities it has
when combined with the other ingredients, the function it is
intended to perform, and whether persons reasonably 18 Syllabus

															skilled in the art would have known of the interchangeability of
an ingredient not contained in the patent with one that was. Pp.
24-25.

															(b) This Court rejects petitioner's primary argument, that the
doctrine of equivalents, as set out in Graver Tank in 1950,
is inconsistent with, and thus did not survive, particular aspects
of Congress' 1952 revision of the Patent Act, 35 U. S. C. § 100 et seq. Petitioner's first three arguments in this
regard-that the doctrine (1) is inconsistent with § 112's
requirement that a patentee specifically "claim" the covered
invention, (2) circumvents the patent reissue process under
§§251-252, and (3) is inconsistent with the primacy of the Patent
and Trademark Office (PTO) in setting a patent's scope-were made in Graver Tank, supra, at 613-615, and n. 3, in the context of
the 1870 Patent Act, and failed to command a majority. The 1952 Act
is not materially different from the 1870 Act with regard to these
matters. Also unpersuasive is petitioner's fourth argument, that
the doctrine of equivalents was implicitly rejected as a general
matter by Congress' specific and limited inclusion of it in § 112,
, 6. This new provision was enacted as a targeted cure in response
to Halliburton Oil Well Cementing Co. v. Walker, 329 U. S. 1 , 8, and
thereby to allow so-called "means" claims describing an element of
an invention by the result accomplished or the function served.
Moreover, the statutory reference to "equivalents" appears to be no
more than a prophylactic against potential side effects of that
cure, i. e., an attempt to limit the application of the
broad literal language of "means" claims to those means that are
"equivalent" to the actual means shown in the patent specification.
Pp. 25-28.

															(c) The determination of equivalence should be applied as an
objective inquiry on an element-by-element basis. The Court is
concerned that the doctrine, as it has come to be broadly applied
since Graver Tank, conflicts with the Court's numerous
holdings that a patent may not be enlarged beyond the scope of its
claims. The way to reconcile the two lines of authority is to apply
the doctrine to each of the individual elements of a claim, rather
than to the accused product or process as a whole. Doing so will
preserve some meaning for each of a claim's elements, all of which
are deemed material to defining the invention's scope. So long as
the doctrine does not encroach beyond these limits, or beyond
related limits discussed in the Court's opinion, infra, at
30-34, 39, n. 8, and 39-40, it will not vitiate the central
functions of patent claims to define the invention and to notify
the public of the patent's scope. pp. 28-30.

															(d) Petitioner is correct that Graver Tank did not
supersede the well-established limitation on the doctrine of
equivalents known as "prosecution history estoppel," whereby a
surrender of subject matter during patent prosecution may preclude
recapturing any part of that 19 subject matter, even if it is equivalent to the matter expressly
claimed. But petitioner reaches too far in arguing that any such
surrender establishes a bright line beyond which no equivalents may
be claimed, and that the reason for an amendment during patent
prosecution is therefore irrelevant to any subsequent estoppel.
There are a variety of reasons why the PTO may request a change in
claim language, and if the patent holder demonstrates that an
amendment had a purpose unrelated to patentability, a court must
consider that purpose in order to decide whether an estoppel is
precluded. Where the patent holder is unable to establish such a
purpose, the court should presume that the purpose behind the
required amendment is such that prosecution history estoppel would
apply. Here, it is undisputed that the upper limit of 9.0 pH was
added to the '746 patent in order to distinguish the Booth patent,
but the record before this Court does not reveal the reason for
adding the lower 6.0 pH limit. It is therefore impossible to tell
whether the latter reason could properly avoid an estoppel. Pp.
30-34.

															(e) The Court rejects petitioner's argument that Graver
Tank requires judicial exploration of the intent of the alleged
infringer or a case's other equities before allowing application of
the doctrine of equivalents. Although Graver Tank certainly
leaves room for the inclusion of intent-based elements in the
doctrine, the Court does not read the case as requiring proof of
intent. The better view, and the one consistent with Graver
Tank's predecessors, see, e. g., Winans v. Denmead, 15 How. 330, 343, and the objective approach to
infringement, is that intent plays no role in the doctrine's
application. Pp. 34-36.

															(f) The Court also rejects petitioner's proposal that in order
to minimize conflict with the notice function of patent claims, the
doctrine of equivalents should be limited to equivalents that are
disclosed within the patent itself. Insofar as the question under
the doctrine is whether an accused element is equivalent to a
claimed element, the proper time for evaluating equivalency-and
knowledge of interchangeability between elements-is at the time of
infringement, not at the time the patent was issued. P. 37.

															(g) The Court declines to consider whether application of the
doctrine of equivalents is a task for the judge or for the jury,
since resolution of that question is not necessary to answer the
question here presented. Pp. 37-39.

															(h) In the Court's view, the particular linguistic framework
used to determine "equivalence," whether the so-called "triple
identity" test or the "insubstantial differences" test, is less
important than whether the test is probative of the essential
inquiry: Does the accused product or process contain elements
identical or equivalent to each claimed element of the patented
invention? Different linguistic frameworks 20 Syllabus

															may be more suitable to different cases, depending on their
particular facts. The Court leaves it to the Federal Circuit's
sound judgment in this area of its special expertise to refine the
formulation of the test for equivalence in the orderly course of
case-by-case determinations. pp.39-40.

															2. Because the Federal Circuit did not consider all of the
requirements of the doctrine of equivalents as described by the
Court in this case, particularly as related to prosecution history
estoppel and the preservation of some meaning for each element in a
claim, further proceedings are necessary. Pp. 40-41. 62 F.3d
1512 , reversed and remanded.

															THOMAS, J., delivered the opinion for a unanimous Court.
GINSBURG, J., filed a concurring opinion, in which KENNEDY, J.,
joined, post, p. 41. Richard G. Taranto argued the cause for
petitioner. With him on the briefs were H. Bartow Farr III and J. Robert Chambers. Deputy Solicitor General Wallace argued the cause for the United
States as amicus curiae. With him on the brief were Solicitor
General Days, Assistant Attorney General Bingaman, Cornelia T. L.
Pillard, Nancy J. Linck, and Albin F. Drost. David E. Schmit argued the cause and filed a brief for
respondent. *

															*Briefs of amici curiae urging reversal were filed for
Gateway Technologies, Inc., by Richard Grant Lyon; for GHZ
Equipment Co. by Ronald D. Maines and Richard G. Wilkins; for the Information Technology Industry Council et
al. by Joel M. Freed, Jerrold J. Ganzfried,
John F. Cooney, and William D. Coston; for the
Intellectual Property Owners by Carter G. Phillips, Mark
E. Haddad, and Joseph R. Guerra; for MCI
Telecommunications Corp. by Paul M. Smith and Nory
Miller; for Micron Separations, Inc., by Steven M. Bauer and John J. Cotter; and for Seagate
Technology, Inc., et al. by Carrie L. Walthour, Karl A. Limbach,
Deborah BaileyWells, and Edward P. Heller III. Briefs of amici curiae urging affirmance were filed for
the Biotechnology Industry Organization by Charles E.
Ludlam; for Chiron Corp. by Donald S. Chisum; for
the Dallas-Fort Worth Intellectual Property Law Association by Lawrence J. Bassuk; for Litton Systems, Inc.,
by Laurence 21 JUSTICE THOMAS delivered the opinion of the Court. Nearly 50
years ago, this Court in Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U. S. 605 (1950), set
out the modern contours of what is known in patent law as the
"doctrine of equivalents." Under this doctrine, a product or
process that does not literally infringe upon the express terms of
a patent claim may nonetheless be found to infringe if there is
"equivalence" between the elements of the accused product or
process and the claimed elements of the patented invention. Id., at 609. Petitioner, which was found to have infringed
upon respondent's patent under the doctrine of equivalents, invites
us to speak the death of that doctrine. We decline that invitation.
The significant disagreement within the Court of Appeals for the
Federal Circuit concerning the application of Graver Tank suggests, however, that the doctrine is not free from confusion. We
therefore will endeavor to clarify the proper scope of the
doctrine.

															I

															The essential facts of this case are few. Petitioner
Warner-Jenkinson Co. and respondent Hilton Davis Chemical Co.
manufacture dyes. Impurities in those dyes must be removed. Hilton
Davis holds United States Patent No. 4,560,746 ('746 patent), which
discloses an improved purification process involving
"ultrafiltration." The '746 process filters impure dye through a
porous membrane at certain

															H. Tribe and Jonathan S. Massey; and for the Ohio State Bar
Association by Eugene P. Whetzel and Albert L. Bell.

															Briefs of amici curiae were filed for the American
Automobile Manufacturers Association by D. Dennis Allegretti,
Phillip D. Brady, and Andrew D. Koblenz; for the
American Intellectual Property Law Association by Robert J. Baechtold, Stevan J. Bosses, Nicholas M.
Cannella, Charles L. Gholz, and Roger W Parkhurst; for
the Chemical Manufacturers Association by Robert A. Armitage and Michael P. Walls; and for the Licensing Executive
Society (D. S. A. and Canada), Inc., by Gayle Parker and James W Gould. 22 pressures and pH levels,l resulting in a high purity dye
product.

															The '746 patent issued in 1985. As relevant to this case, the
patent claims as its invention an improvement in the
ultrafiltration process as follows: "In a process for the purification of a dye ... the improvement
which comprises: subjecting an aqueous solution ... to
ultrafiltration through a membrane having a nominal pore diameter
of 5-15 Angstroms under a hydrostatic pressure of approximately 200
to 400 p.s.i.g., at a pH from approximately 6.0 to 9.0, to
thereby cause separation of said impurities from said dye .... "
App. 36-37 (emphasis added). The inventors added the phrase "at a pH from approximately 6.0
to 9.0" during patent prosecution. At a minimum, this phrase was
added to distinguish a previous patent (the "Booth" patent) that
disclosed an ultrafiltration process operating at a pH above 9.0.
The parties disagree as to why the low-end pH limit of 6.0 was
included as part of the claim.2

															1 The pH, or power (exponent) of Hydrogen, of a solution is a
measure of its acidity or alkalinity. A pH of 7.0 is neutral; a pH
below 7.0 is acidic; and a pH above 7.0 is alkaline. Although
measurement of pH is on a logarithmic scale, with each whole number
difference representing a tenfold difference in acidity, the
practical significance of any such difference will often depend on
the context. Pure water, for example, has a neutral pH of 7.0,
whereas carbonated water has an acidic pH of 3.0, and concentrated
hydrochloric acid has a pH approaching 0.0. On the other end of the
scale, milk of magnesia has a pH of 10.0, whereas household ammonia
has a pH of 11.9. 21 Encyclopedia Americana 844 (Int'l ed.
1990).

															2 Petitioner contends that the lower limit was added because
below a pH of 6.0 the patented process created "foaming" problems
in the plant and because the process was not shown to work below
that pH level. Brief for Petitioner 4, n. 5,37, n. 28. Respondent
counters that the process was successfully tested to pH levels as
low as 2.2 with no effect on the process because of foaming, but
offers no particular explanation as to why the lower level of 6.0
pH was selected. Brief for Respondent 34, n. 34. 23 In 1986, Warner-Jenkinson developed an ultrafiltration process
that operated with membrane pore diameters assumed to be 5-15
Angstroms, at pressures of 200 to nearly 500 p. s. i. g., and at a
pH of 5.0. Warner-Jenkinson did not learn of the '746 patent until
after it had begun commercial use of its ultrafiltration process.
Hilton Davis eventually learned of Warner-Jenkinson's use of
ultrafiltration and, in 1991, sued Warner-Jenkinson for patent
infringement.

															As trial approached, Hilton Davis conceded that there was no
literal infringement, and relied solely on the doctrine of
equivalents. Over Warner-Jenkinson's objection that the doctrine of
equivalents was an equitable doctrine to be applied by the court,
the issue of equivalence was included among those sent to the jury.
The jury found that the '746 patent was not invalid and that
Warner-Jenkinson infringed upon the patent under the doctrine of
equivalents. The jury also found, however, that Warner-Jenkinson
had not intentionally infringed, and therefore awarded only 20% of
the damages sought by Hilton Davis. The District Court denied
Warner-Jenkinson's post-trial motions, and entered a permanent
injunction prohibiting Warner-Jenkinson from practicing
ultrafiltration below 500 p. s. i. g. and below 9.01 pH. A
fractured en banc Court of Appeals for the Federal Circuit
affirmed. 62 F.3d
1512 (1995).

															The majority below held that the doctrine of equivalents
continues to exist and that its touchstone is whether substantial
differences exist between the accused process and the patented
process. Id., at 1521-1522. The court also held that the
question of equivalence is for the jury to decide and that the jury
in this case had substantial evidence from which it could conclude
that the Warner-Jenkinson process was not substantially different
from the ultrafiltration process disclosed in the '746 patent. Id., at 1525.

															There were three separate dissents, commanding a total of 5 of
12 judges. Four of the five dissenting judges viewed the doctrine
of equivalents as allowing an improper expan- 24 sion of claim scope, contrary to this Court's numerous holdings
that it is the claim that defines the invention and gives notice to
the public of the limits of the patent monopoly. Id., at
1537-1538 (opinion of Plager, J.). The fifth dissenter, the late
Judge Nies, was able to reconcile the prohibition against enlarging
the scope of claims and the doctrine of equivalents by applying the
doctrine to each element of a claim, rather than to the accused
product or process "overall." Id., at 1574. As she explained
it: "The 'scope' is not enlarged if courts do not go beyond the
substitution of equivalent elements." Ibid. All of the
dissenters, however, would have found that a much narrowed doctrine
of equivalents may be applied in whole or in part by the court. Id., at 1540-1542 (opinion of Plager, J.); id., at
1579 (opinion of Nies, J.).

															We granted certiorari, 516 U. S. 1145 (1996), and now reverse
and remand.

															II

															In Graver Tank we considered the application of the
doctrine of equivalents to an accused chemical composition for use
in welding that differed from the patented welding material by the
substitution of one chemical element. 339 U. S., at 610. The
substituted element did not fall within the literal terms of the
patent claim, but the Court nonetheless found that the "question
which thus emerges is whether the substitution [of one element for
the other] ... is a change of such substance as to make the
doctrine of equivalents inapplicable; or conversely, whether under
the circumstances the change was so insubstantial that the trial
court's invocation of the doctrine of equivalents was justified." Ibid. The Court also described some of the considerations
that go into applying the doctrine of equivalents: "What constitutes equivalency must be determined against the
context of the patent, the prior art, and the particular
circumstances of the case. Equivalence, in the patent law, is not
the prisoner of a formula and is 25 not an absolute to be considered in a vacuum. It does not
require complete identity for every purpose and in every respect.
In determining equivalents, things equal to the same thing may not
be equal to each other and, by the same token, things for most
purposes different may sometimes be equivalents. Consideration must
be given to the purpose for which an ingredient is used in a
patent, the qualities it has when combined with the other
ingredients, and the function which it is intended to perform. An
important factor is whether persons reasonably skilled in the art
would have known of the interchangeability of an ingredient not
contained in the patent with one that was." Id., at 609. Considering those factors, the Court viewed the difference
between the chemical element claimed in the patent and the
substitute element to be "colorable only," and concluded that the
trial court's judgment of infringement under the doctrine of
equivalents was proper. Id., at 612.

															A

															Petitioner's primary argument in this Court is that the doctrine
of equivalents, as set out in Graver Tank in 1950, did not
survive the 1952 revision of the Patent Act, 35 U. s. C. § 100 et seq., because it is inconsistent with several aspects of
that Act. In particular, petitioner argues: (1) The doctrine of
equivalents is inconsistent with the statutory requirement that a
patentee specifically "claim" the invention covered by a patent, §
112; (2) the doctrine circumvents the patent reissue
process-designed to correct mistakes in drafting or the like-and
avoids the express limitations on that process, §§ 251-252; (3) the
doctrine is inconsistent with the primacy of the Patent and
Trademark Office (PTO) in setting the scope of a patent through the
patent prosecution process; and (4) the doctrine was implicitly
rejected as a general matter by Congress' specific and limited
inclusion of the doctrine 26 in one section regarding "means" claiming, § 112, , 6. All but
one of these arguments were made in Graver Tank in the
context of the 1870 Patent Act, and failed to command a
majority.3

															The 1952 Patent Act is not materially different from the 1870
Act with regard to claiming, reissue, and the role of the PTO.
Compare, e. g., 35 U. S. C. § 112 ("The specification
shall conclude with one or more claims particularly pointing out
and distinctly claiming the subject matter which the applicant
regards as his invention") with the Consolidated Patent Act of
1870, ch. 230, § 26, 16 Stat. 198, 201 (the applicant "shall
particularly point out and distinctly claim the part, improvement,
or combination which he claims as his invention or discovery").
Such minor differences as exist between those provisions in the
1870 and the 1952 Acts have no bearing on the result reached in Graver Tank, and thus provide no basis for our overruling
it. In the context of infringement, we have already held that
pre-1952 precedent survived the passage of the 1952 Act. See Aro
Mfg. Co. v. Convertible Top Replacement Co., 365 U. S. 336 , 342 (1961)
(new section defining infringement "left intact the entire 3 Graver Tank was decided over a vigorous dissent.
In that dissent, Justice Black raised the first three of
petitioner's four arguments against the doctrine of equivalents.
See 339 U. S., at 613-614 (doctrine inconsistent with statutory
requirement to "distinctly claim" the invention); id., at
614-615 (patent reissue process available to correct mistakes); id., at 615, n. 3 (duty lies with the Patent Office to
examine claims and to conform them to the scope of the invention;
inventors may appeal Patent Office determinations if they disagree
with result).

															Indeed, petitioner's first argument was not new even in 1950.
Nearly 100 years before Graver Tank, this Court approved of
the doctrine of equivalents in Winans v. Denmead, 15
How. 330 (1854). The dissent in Winans unsuccessfully argued
that the majority result was inconsistent with the requirement in
the 1836 Patent Act that the applicant "particularly 'specify and
point' out what he claims as his invention," and that the patent
protected nothing more. Id., at 347 (opinion of Campbell,
J.). 27 body of case law on direct infringement"). We see no reason to
reach a different result here.4

															Petitioner's fourth argument for an implied congressional
negation of the doctrine of equivalents turns on the reference to
"equivalents" in the "means" claiming provision of the 1952 Act.
Section 112, , 6, a provision not contained in the 1870 Act,
states: "An element in a claim for a combination may be expressed as a
means or step for performing a specified function without the
recital of structure, material, or acts in support thereof, and
such claim shall be construed to cover the corresponding structure,
material, or acts described in the specification and equivalents
thereof" (Emphasis added.) Thus, under this new provision, an applicant can describe an
element of his invention by the result accomplished or the function
served, rather than describing the item or element to be used (e. g., "a means of connecting Part A to Part B," rather
than "a two-penny nail"). Congress enacted § 112, , 6, in response
to Halliburton Oil Well Cementing Co. v. Walker, 329 U. S. 1 (1946),
which rejected claims that "do not describe the invention but use
'conveniently functional language at the exact point of novelty.'" Id., at 8 (citation

															4 Petitioner argues that the evolution in patent practice from
"central" claiming (describing the core principles of the
invention) to "peripheral" claiming (describing the outer
boundaries of the invention) requires that we treat Graver
Tank as an aberration and abandon the doctrine of equivalents.
Brief for Petitioner 43-45. We disagree. The suggested change in
claiming practice predates Graver Tank, is not of statutory
origin, and seems merely to reflect narrower inventions in more
crowded arts. Also, judicial recognition of so-called "pioneer"
patents suggests that the abandonment of "central" claiming may be
overstated. That a claim describing a limited improvement in a
crowded field will have a limited range of permissible equivalents
does not negate the availability of the doctrine vel
non. 28 omitted). See In re Donaldson Co., 16
F.3d 1189 , 1194 (CA Fed. 1994) (Congress enacted predecessor of
§ 112, , 6, in response to Halliburton); In re Fuetterer, 319 F.2d
259 , 264, n. 11 (CCPA 1963) (same); see also 2 D. Chisum,
Patents § 8.04[2], pp. 63-64 (1996) (discussing 1954 commentary of
then-Chief Patent Examiner P. J. Federico). Section 112, , 6, now
expressly allows so-called "means" claims, with the proviso that
application of the broad literal language of such claims must be
limited to only those means that are "equivalen[t]" to the actual
means shown in the patent specification. This is an application of
the doctrine of equivalents in a restrictive role, narrowing the
application of broad literal claim elements. We recognized this
type of role for the doctrine of equivalents in Graver Tank itself. 339 U. S., at 608-609. The added provision, however, is
silent on the doctrine of equivalents as applied where there is no
literal infringement.

															Because § 112, , 6, was enacted as a targeted cure to a specific
problem, and because the reference in that provision to
"equivalents" appears to be no more than a prophylactic against
potential side effects of that cure, such limited congressional
action should not be overread for negative implications. Congress
in 1952 could easily have responded to Graver Tank as it did
to the Halliburton decision. But it did not. Absent
something more compelling than the dubious negative inference
offered by petitioner, the lengthy history of the doctrine of
equivalents strongly supports adherence to our refusal in Graver
Tank to find that the Patent Act conflicts with that doctrine.
Congress can legislate the doctrine of equivalents out of existence
any time it chooses. The various policy arguments now made by both
sides are thus best addressed to Congress, not this Court.

															B

															We do, however, share the concern of the dissenters below that
the doctrine of equivalents, as it has come to be applied since Graver Tank, has taken on a life of its own, unbounded 29 by the patent claims. There can be no denying that the doctrine
of equivalents, when applied broadly, conflicts with the
definitional and public-notice functions of the statutory claiming
requirement. Judge Nies identified one means of avoiding this
conflict: "[A] distinction can be drawn that is not too esoteric between
substitution of an equivalent for a component in an
invention and enlarging the metes and bounds of the invention beyond what is claimed. "Where a claim to an invention is expressed as a combination of
elements, as here, 'equivalents' in the sobriquet 'Doctrine of
Equivalents' refers to the equivalency of an element or part of the invention with one that is substituted in the
accused product or process. "This view that the accused device or process must be more than
'equivalent' overall reconciles the Supreme Court's position
on infringement by equivalents with its concurrent statements that
'the courts have no right to enlarge a patent beyond the scope of
its claims as allowed by the Patent Office.' [Citations omitted.]
The 'scope' is not enlarged if courts do not go beyond the
substitution of equivalent elements." 62 F. 3d, at 15731574
(dissenting opinion) (emphasis in original). We concur with this apt reconciliation of our two lines of
precedent. Each element contained in a patent claim is deemed
material to defining the scope of the patented invention, and thus
the doctrine of equivalents must be applied to individual elements
of the claim, not to the invention as a whole. It is important to
ensure that the application of the doctrine, even as to an
individual element, is not allowed such broad playas to effectively
eliminate that element in its entirety. So long as the doctrine of
equivalents does not encroach beyond the limits just described, or
beyond related 30 limits to be discussed infra this page and 31-34, 39, n.
8, and 39-40, we are confident that the doctrine will not vitiate
the central functions of the patent claims themselves.

															III

															Understandably reluctant to assume this Court would overrule Graver Tank, petitioner has offered alternative arguments in
favor of a more restricted doctrine of equivalents than it feels
was applied in this case. We address each in turn.

															A

															Petitioner first argues that Graver Tank never purported
to supersede a well-established limit on nonliteral infringement,
known variously as "prosecution history estoppel" and "file wrapper
estoppel." See Bayer Aktiengesellschaft v. Duphar Int'Z
Research B. V:, 738 F.2d
1237 , 1238 (CA Fed. 1984). According to petitioner, any
surrender of subject matter during patent prosecution, regardless
of the reason for such surrender, precludes recapturing any part of
that subject matter, even if it is equivalent to the matter
expressly claimed. Because, during patent prosecution, respondent
limited the pH element of its claim to pH levels between 6.0 and
9.0, petitioner would have those limits form bright lines beyond
which no equivalents may be claimed. Any inquiry into the reasons
for a surrender, petitioner claims, would undermine the public's
right to clear notice of the scope of the patent as embodied in the
patent file.

															We can readily agree with petitioner that Graver Tank did
not dispose of prosecution history estoppel as a legal limit ation
on the doctrine of equivalents. But petitioner reaches too far in
arguing that the reason for an amendment during patent prosecution
is irrelevant to any subsequent estoppel. In each of our cases
cited by petitioner and by the dissent below, prosecution history
estoppel was tied to amendments made to avoid the prior art, or
otherwise to address a specific concern-such as obviousness-that
arguably would have 31 rendered the claimed subject matter unpatentable. Thus, in Exhibit Supply Co. v. Ace Patents Corp., 315 U. S. 126 (1942),
Chief Justice Stone distinguished inclusion of a limiting phrase in
an original patent claim from the "very different" situation in
which "the applicant, in order to meet objections in the Patent
Office, based on references to the prior art, adopted the
phrase as a substitute for the broader one" previously used. Id., at 136 (emphasis added). Similarly, in Keystone
Driller Co. v. Northwest Engineering Corp., 294 U. S. 42 (1935),
estoppel was applied where the initial claims were "rejected on the
prior art," id., at 48, n. 6, and where the allegedly
infringing equivalent element was outside of the revised claims and
within the prior art that formed the basis for the rejection of the
earlier claims, id., at 48.5

															It is telling that in each case this Court probed the reasoning
behind the Patent Office's insistence upon a change in the claims.
In each instance, a change was demanded because the claim as
otherwise written was viewed as not describing a patentable
invention at all-typically because what it described was
encompassed within the prior art. But, as the United States informs
us, there are a variety of other reasons why the PTO may request a
change in claim language. Brief for United States as Amicus
Curiae 22-23 5 See also Smith v. Magic City Kennel Club, Inc., 282 U. S. 784 ,
788 (1931) (estoppel applied to amended claim where the original
"claim was rejected on the prior patent to" another); Computing
Scale Co. of America v. Automatic Scale Co., 204 U. S. 609 , 618-620
(1907) (initial claims rejected based on lack of invention over
prior patents); Hubbell v. United States, 179 U. S. 77 , 83 (1900)
(patentee estopped from excluding a claim element where element was
added to overcome objections based on lack of novelty over prior
patents); Sutter v. Robinson, 119 U. S. 530 , 541 (1886)
(estoppel applied where, during patent prosecution, the applicant
"was expressly required to state that [the device's] structural
plan was old and not of his invention"); cf. Graham v. John Deere Co. of Kansas City, 383 U. S. 1, 33 (1966)
(noting, in a validity determination, that "claims that have been
narrowed in order to obtain the issuance of a patent by
distinguishing the prior art cannot be sustained to cover that
which was previously by limitation eliminated from the
patent"). 32 (counsel for the PTO also appearing on the brief). And if the
PTO has been requesting changes in claim language without the
intent to limit equivalents or, indeed, with the expectation that
language it required would in many cases allow for a range of
equivalents, we should be extremely reluctant to upset the basic
assumptions of the PTO without substantial reason for doing so. Our
prior cases have consistently applied prosecution history estoppel
only where claims have been amended for a limited set of reasons,
and we see no substantial cause for requiring a more rigid rule
invoking an estoppel regardless of the reasons for a change.6

															In this case, the patent examiner objected to the patent claim
due to a perceived overlap with the Booth patent, which revealed an
ultrafiltration process operating at a pH above 9.0. In response to
this objection, the phrase "at a pH from approximately 6.0 to 9.0"
was added to the claim. While it is undisputed that the upper limit
of 9.0 was added in order to distinguish the Booth patent, the
reason for adding the lower limit of 6.0 is unclear. The lower
limit certainly did not serve to distinguish the Booth patent,
which said nothing about pH levels below 6.0. Thus, while a lower
limit of 6.0, by its mere inclusion, became a material element of the claim, that did not necessarily preclude the
application of the doctrine of equivalents as to that element. See Hub bell v. United States, 179 U. S. 77 , 82 (1900) ("
'[A]ll [specified elements] must be regarded as material,'" though
it remains an open "'question whether an omitted part is supplied
by an equivalent device or instrumentality'" (citation
omitted)).

															6 That petitioner's rule might provide a brighter line for
determining whether a patentee is estopped under certain
circumstances is not a sufficient reason for adopting such a rule.
This is especially true where, as here, the PTO may have relied
upon a flexible rule of estoppel when deciding whether to ask for a
change in the first place. To change so substantially the rules of
the game now could very well subvert the various balances the PTO
sought to strike when issuing the numerous patents which have not
yet expired and which would be affected by our decision. 33 Where the reason for the change was not related to avoiding the
prior art, the change may introduce a new element, but it does not
necessarily preclude infringement by equivalents of that
element.7

															We are left with the problem, however, of what to do in a case
like the one at bar, where the record seems not to reveal the
reason for including the lower pH limit of 6.0. In our view,
holding that certain reasons for a claim amendment may avoid the
application of prosecution history estoppel is not tantamount to
holding that the absence of a reason for an amendment may
similarly avoid such an estoppel. Mindful that claims do indeed
serve both a definitional and a notice function, we think the
better rule is to place the burden on the patent holder to
establish the reason for an amendment required during patent
prosecution. The court then would decide whether that reason is
sufficient to overcome prosecution history estoppel as a bar to
application of the doctrine of equivalents to the element added by
that amendment. Where no explanation is established, however, the
court should presume that the patent applicant had a substantial
reason related to patentability for including the limiting element
added by amendment. In those circumstances, prosecution history
estoppel would bar the application of the doctrine of equivalents
as to that element. The presumption we have described, one subject
to rebuttal if an appropriate reason for a required amendment is
established, gives proper deference to the role of claims in
defining an invention and providing public notice, and to the
primacy of

															7We do not suggest that, where a change is made to overcome an
objection based on the prior art, a court is free to review the
correctness of that objection when deciding whether to apply
prosecution history estoppel. As petitioner rightly notes, such
concerns are properly addressed on direct appeal from the denial of
a patent, and will not be revisited in an infringement action. Smith v. Magic City Kennel Club, Inc., supra, at
789-790. What is permissible for a court to explore is the
reason (right or wrong) for the objection and the manner in which
the amendment addressed and avoided the objection. 34 the PTO in ensuring that the claims allowed cover only subject
matter that is properly patentable in a proffered patent
application. Applied in this fashion, prosecution history estoppel
places reasonable limits on the doctrine of equivalents, and
further insulates the doctrine from any feared conflict with the
Patent Act.

															Because respondent has not proffered in this Court a reason for
the addition of a lower pH limit, it is impossible to tell whether
the reason for that addition could properly avoid an estoppel.
Whether a reason in fact exists, but simply was not adequately
developed, we cannot say. On remand, the Federal Circuit can
consider whether reasons for that portion of the amendment were
offered or not and whether further opportunity to establish such
reasons would be proper.

															B

															Petitioner next argues that even if Graver Tank remains
good law, the case held only that the absence of substantial
differences was a necessary element for infringement under
the doctrine of equivalents, not that it was sufficient for
such a result. Brief for Petitioner 32. Relying on Graver
Tank's references to the problem of an "unscrupulous copyist"
and "piracy," 339 U. S., at 607, petitioner would require judicial
exploration of the equities of a case before allowing application
of the doctrine of equivalents. To be sure, Graver Tank refers to the prevention of copying and piracy when describing the
benefits of the doctrine of equivalents. That the doctrine produces
such benefits, however, does not mean that its application is
limited only to cases where those particular benefits are
obtained.

															Elsewhere in Graver Tank the doctrine is described in
more neutral terms. And the history of the doctrine as relied upon
by Graver Tank reflects a basis for the doctrine not so
limited as petitioner would have it. In Winans v. Denmead, 15 How. 330, 343 (1854), we described the
doctrine 35 of equivalents as growing out of a legally implied term in each
patent claim that "the claim extends to the thing patented, however
its form or proportions may be varied." Under that view,
application of the doctrine of equivalents involves determining
whether a particular accused product or process infringes upon the
patent claim, where the claim takes the form-half express, half
implied-of "X and its equivalents." Machine Co. v. Murphy, 97 U. S. 120 , 125 (1878),
on which Graver Tank also relied, offers a similarly
intent-neutral view of the doctrine of equivalents: "[T]he substantial equivalent of a thing, in the sense of the
patent law, is the same as the thing itself; so that if two devices
do the same work in substantially the same way, and accomplish
substantially the same result, they are the same, even though they
differ in name, form, or shape." If the essential predicate of the doctrine of equivalents is the
notion of identity between a patented invention and its equivalent,
there is no basis for treating an infringing equivalent any
differently from a device that infringes the express terms of the
patent. Application of the doctrine of equivalents, therefore, is
akin to determining literal infringement, and neither requires
proof of intent.

															Petitioner also points to Graver Tank's seeming reliance
on the absence of independent experimentation by the alleged
infringer as supporting an equitable defense to the doctrine of
equivalents. The Federal Circuit explained this factor by
suggesting that an alleged infringer's behavior, be it copying,
designing around a patent, or independent experimentation,
indirectly reflects the substantiality of the differences between
the patented invention and the accused device or process. According
to the Federal Circuit, a person aiming to copy or aiming to avoid
a patent is imagined to be at 36 least marginally skilled at copying or avoidance, and thus
intentional copying raises an inference-rebuttable by proof of
independent development-of having only insubstantial differences,
and intentionally designing around a patent claim raises an
inference of substantial differences. This explanation leaves much
to be desired. At a minimum, one wonders however to distinguish
between the intentional copyist making minor changes to lower the
risk of legal action and the incremental innovator designing around
the claims, yet seeking to capture as much as is permissible of the
patented advance.

															But another explanation is available that does not require a
divergence from generally objective principles of patent
infringement. In both instances in Graver Tank where we
referred to independent research or experiments, we were discussing
the known interchangeability between the chemical compound claimed
in the patent and the compound substituted by the alleged
infringer. The need for independent experimentation thus could
reflect knowledge-or lack thereof-of interchangeability possessed
by one presumably skilled in the art. The known interchangeability
of substitutes for an element of a patent is one of the express
objective factors noted by Graver Tank as bearing upon
whether the accused device is substantially the same as the
patented invention. Independent experimentation by the alleged
infringer would not always reflect upon the objective question
whether a person skilled in the art would have known of the
interchangeability between two elements, but in many cases it would
likely be probative of such knowledge.

															Although Graver Tank certainly leaves room for
petitioner's suggested inclusion of intent-based elements in the
doctrine of equivalents, we do not read it as requiring them. The
better view, and the one consistent with Graver Tank's predecessors and the objective approach to infringement, is that
intent plays no role in the application of the doctrine of
equivalents. 37 C

															Finally, petitioner proposes that in order to minimize conflict
with the notice function of patent claims, the doctrine of
equivalents should be limited to equivalents that are disclosed
within the patent itself. A milder version of this argument, which
found favor with the dissenters below, is that the doctrine should
be limited to equivalents that were known at the time the patent
was issued, and should not extend to after-arising equivalents.

															As we have noted, supra, at 36, with regard to the
objective nature of the doctrine, a skilled practitioner's
knowledge of the interchangeability between claimed and accused
elements is not relevant for its own sake, but rather for what it
tells the factfinder about the similarities or differences between
those elements. Much as the perspective of the hypothetical
"reasonable person" gives content to concepts such as "negligent"
behavior, the perspective of a skilled practitioner provides
content to, and limits on, the concept of "equivalence." Insofar as
the question under the doctrine of equivalents is whether an
accused element is equivalent to a claimed element, the proper time
for evaluating equivalency-and thus knowledge of interchangeability
between elements-is at the time of infringement, not at the time
the patent was issued. And rejecting the milder version of
petitioner's argument necessarily rejects the more severe
proposition that equivalents must not only be known, but must also
be actually disclosed in the patent in order for such equivalents
to infringe upon the patent.

															IV

															The various opinions below, respondents, and amici devote
considerable attention to whether application of the doctrine of
equivalents is a task for the judge or for the jury. However,
despite petitioner's argument below that the doctrine should be
applied by the judge, in this Court petitioner makes only passing
reference to this issue. See Brief for 38 Petitioner 22, n. 15 ("If this Court were to hold in Markman v. Westview Instruments, Inc., No. 95-26
(argued Jan. 8, 1996), that judges rather than juries are to
construe patent claims, so as to provide a uniform definition of
the scope of the legally protected monopoly, it would seem at
crosspurposes to say that juries may nonetheless expand the claims
by resort to a broad notion of 'equivalents' "); Reply Brief for
Petitioner 20 (whether judge or jury should apply the doctrine of
equivalents depends on how the Court views the nature of the
inquiry under the doctrine of equivalents).

															Petitioner's comments go more to the alleged inconsistency
between the doctrine of equivalents and the claiming requirement
than to the role of the jury in applying the doctrine as properly
understood. Because resolution of whether, or how much of, the
application of the doctrine of equivalents can be resolved by the
court is not necessary for us to answer the question presented, we
decline to take it up. The Federal Circuit held that it was for the
jury to decide whether the accused process was equivalent to the
claimed process. There was ample support in our prior cases for
that holding. See, e. g., Machine Co. v. Murphy, 97
U. S., at 125 ("[I]n determining the question of infringement, the
court or jury, as the case may be, ... are to look at the machines
or their several devices or elements in the light of what they do,
or what office or function they perform, and how they perform it,
and to find that one thing is substantially the same as another, if
it performs substantially the same function in substantially the
same way to obtain the same result"); Winans v. Denmead, 15 How., at 344 ("[It] is a question for the jury"
whether the accused device was "the same in kind, and effected by
the employment of [the patentee's] mode of operation in
substance"). Nothing in our recent decision in Markman v. Westview Instruments, Inc., 517 U. S. 370 (1996),
necessitates a different result than that reached by the Federal
Circuit. Indeed, Markman cites with considerable favor, when
discussing the role of judge 39 and jury, the seminal Winans decision. 517 U. S., at
384385. Whether, if the issue were squarely presented to us, we
would reach a different conclusion than did the Federal Circuit is
not a question we need decide today.8

															V

															All that remains is to address the debate regarding the
linguistic framework under which "equivalence" is determined. Both
the parties and the Federal Circuit spend considerable time arguing
whether the so-called "triple identity" test-focusing on the function served by a particular claim element, the way that element serves that function, and the result thus obtained by that element-is a suitable method for determining
equivalence, or whether an "insubstantial differences" approach is
better. There seems to be substantial agreement that, while the
triple identity test may be suitable for analyzing mechanical
devices, it often

															8With regard to the concern over unreviewability due to
black-box jury verdicts, we offer only guidance, not a specific
mandate. Where the evidence is such that no reasonable jury could
determine two elements to be equivalent, district courts are
obliged to grant partial or complete summary judgment. See Fed.
Rule Civ. Proc. 56; Celotex Corp. v. Catrett, 477 U. S. 317 ,
322-323 (1986). If there has been a reluctance to do so by some
courts due to unfamiliarity with the subject matter, we are
confident that the Federal Circuit can remedy the problem. Of
course, the various legal limitations on the application of the
doctrine of equivalents are to be determined by the court, either
on a pretrial motion for partial summary judgment or on a motion
for judgment as a matter of law at the close of the evidence and
after the jury verdict. Fed. Rule Civ. Proc. 56; Fed. Rule Civ.
Proc. 50. Thus, under the particular facts of a case, if
prosecution history estoppel would apply or if a theory of
equivalence would entirely vitiate a particular claim element,
partial or complete judgment should be rendered by the court, as
there would be no further material issue for the jury to
resolve. Finally, in cases that reach the jury, a special verdict
and/or interrogatories on each claim element could be very useful
in facilitating review, uniformity, and possibly postverdict
judgments as a matter of law. See Fed. Rules Civ. Proc. 49 and 50.
We leave it to the Federal Circuit how best to implement procedural
improvements to promote certainty, consistency, and reviewability
to this area of the law. 40 provides a poor framework for analyzing other products or
processes. On the other hand, the insubstantial differences test
offers little additional guidance as to what might render any given
difference "insubstantial."

															In our view, the particular linguistic framework used is less
important than whether the test is probative of the essential
inquiry: Does the accused product or process contain elements
identical or equivalent to each claimed element of the patented
invention? Different linguistic frameworks may be more suitable to
different cases, depending on their particular facts. A focus on
individual elements and a special vigilance against allowing the
concept of equivalence to eliminate completely any such elements
should reduce considerably the imprecision of whatever language is
used. An analysis of the role played by each element in the context
of the specific patent claim will thus inform the inquiry as to
whether a substitute element matches the function, way, and result
of the claimed element, or whether the substitute element plays a
role substantially different from the claimed element. With these
limiting principles as a backdrop, we see no purpose in going
further and micromanaging the Federal Circuit's particular word
choice for analyzing equivalence. We expect that the Federal
Circuit will refine the formulation of the test for equivalence in
the orderly course of case-by-case determinations, and we leave
such refinement to that court's sound judgment in this area of its
special expertise.

															VI

															Today we adhere to the doctrine of equivalents. The
determination of equivalence should be applied as an objective
inquiry on an element-by-element basis. Prosecution history
estoppel continues to be available as a defense to infringement,
but if the patent holder demonstrates that an amendment required
during prosecution had a purpose unrelated to patentability, a
court must consider that purpose in 41 order to decide whether an estoppel is precluded. Where the
patent holder is unable to establish such a purpose, a court should
presume that the purpose behind the required amendment is such that
prosecution history estoppel would apply. Because the Court of
Appeals for the Federal Circuit did not consider all of the
requirements as described by us today, particularly as related to
prosecution history estoppel and the preservation of some meaning
for each element in a claim, we reverse its judgment and remand the
case for further proceedings consistent with this opinion.

															It is so ordered.

															JUSTICE GINSBURG, with whom JUSTICE KENNEDY joins,
concurring.

															I join the opinion of the Court and write separately to add a
cautionary note on the rebuttable presumption the Court announces
regarding prosecution history estoppel. I address in particular the
application of the presumption in this case and others in which
patent prosecution has already been completed. The new presumption,
if applied woodenly, might in some instances unfairly discount the
expectations of a patentee who had no notice at the time of patent
prosecution that such a presumption would apply. Such a patentee
would have had little incentive to insist that the reasons for all
modifications be memorialized in the file wrapper as they were
made. Years after the fact, the patentee may find it difficult to
establish an evidentiary basis that would overcome the new
presumption. The Court's opinion is sensitive to this problem,
noting that "the PTO may have relied upon a flexible rule of
estoppel when deciding whether to ask for a change" during patent
prosecution. Ante, at 32, n. 6.

															Because respondent has not presented to this Court any
explanation for the addition of the lower pH limit, I concur in the
decision to remand the matter to the Federal Circuit. 42 On remand, that court can determine-bearing in mind the prior
absence of clear rules of the game-whether suitable reasons for
including the lower pH limit were earlier offered or, if not,
whether they can now be established.