NOTICE: This opinion is subject to
formal revision before publication in the United States Reports.
Readers are requested to notify the Reporter of Decisions, Supreme
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															SUPREME COURT OF THE UNITED STATES

															_________________

															No. 22–899

															_________________

															JASON SMITH, PETITIONER v. ARIZONA

															on writ of certiorari to the court of appeals
of arizona, division one

															[June 21, 2024]

															Justice Kagan delivered the opinion of the
Court.

															The Sixth Amendment’s Confrontation Clause
guarantees a criminal defendant the right to confront the witnesses
against him. The Clause bars the admission at trial of “testimonial
statements” of an absent witness unless she is “unavailable to
testify, and the defendant ha[s] had a prior opportunity” to
cross-examine her. Crawford v. Washington , 541 U.S.
36 , 53–54 (2004). And that prohibition applies in full to
forensic evidence. So a prosecutor cannot introduce an absent
laboratory analyst’s testimonial out-of-court statements to prove
the results of forensic testing. See Melendez-Diaz v. Massachusetts , 557 U.S.
305 , 307, 329 (2009).

															The question presented here concerns the
application of those principles to a case in which an expert
witness restates an absent lab analyst’s factual assertions to
support his own opinion testimony. This Court has held that the
Confrontation Clause’s requirements apply only when the prosecution
uses out-of-court statements for “the truth of the matter
asserted.” Crawford , 541 U. S., at 60, n. 9. Some
state courts, including the court below, have held that this
condition is not met when an expert recites another analyst’s
statements as the basis for his opinion. Today, we reject that
view. When an expert conveys an absent analyst’s statements in
support of his opinion, and the statements provide that support
only if true, then the statements come into evidence for their
truth. As this dispute illustrates, that will generally be the case
when an expert relays an absent lab analyst’s statements as part of
offering his opinion. And if those statements are testimonial
too—an issue we briefly address but do not resolve as to this
case—the Confrontation Clause will bar their admission.

															I

															A

															The Confrontation Clause provides that “[i]n
all criminal prosecutions, the accused shall enjoy the right
. . . to be confronted with the witnesses against him.”
In operation, the Clause protects a defendant’s right of
cross-examination by limiting the prosecution’s ability to
introduce statements made by people not in the courtroom. For a
time, this Court held that the Clause’s “preference for
face-to-face” confrontation could give way if a court found that an
out-of-court statement bore “adequate indicia of reliability.” Ohio v. Roberts , 448 U.S.
56 , 65–66 (1980). But two decades ago, the Court changed
course, to better reflect original understandings. In Crawford v. Washington , the Court deemed it
“fundamentally at odds with the right of confrontation” to admit
statements based on judicial determinations of reliability. 541
U. S., at 61. The Clause, Crawford explained,
“commands[ ] not that evidence be reliable, but that
reliability be assessed in a particular manner: by testing in the
crucible of cross-examination.” Ibid. And so the Clause bars
the admission at trial of an absent witness’s statements—however
trustworthy a judge might think them—unless the witness is
unavailable and the defendant had a prior chance to subject her to
cross-examination.

															But not always. The Clause’s prohibition
“applies only to testimonial hearsay”—and in that two-word phrase
are two limits. Davis v. Washington , 547 U.S.
813 , 823 (2006). First, in speaking about “witnesses”—or “those
who bear testimony”—the Clause confines itself to “testimonial
statements,” a category whose contours we have variously described. Id. , at 823, 826; see id. , at 822 (statements “made
in the course of police interrogation” were testimonial when “the
primary purpose of the interrogation [was] to establish or prove
past events potentially relevant to later criminal prosecution”); Michigan v. Bryant , 562 U.S.
344 , 358, 359 (2011) (statements made to police “to meet an
ongoing emergency” were “not procured with a primary purpose of
creating an out-of-court substitute for trial testimony”); Melendez-Diaz , 557 U. S., at 311 (testimonial
certificates of the results of forensic analysis were created
“under circumstances which would lead an objective witness
reasonably to believe that the statement[s] would be available for
use at a later trial”); infra , at 19. Second and more
relevant here, the Clause bars only the introduction of
hearsay—meaning, out-of-court statements offered “to prove the
truth of the matter asserted.” Anderson v. United
States , 417 U.S.
211 , 219 (1974). When a statement is admitted for a reason
unrelated to its truth, we have held, the Clause’s “role in
protecting the right of cross-examination” is not implicated. Tennessee v. Street , 471 U.S.
409 , 414 (1985); see Anderson , 417 U. S., at 220.
That is because the need to test an absent witness ebbs when her
truthfulness is not at issue. See ibid. ; Street , 471
U. S., at 414; infra , at 13–14, 17.

															Not long after Crawford , the Court made
clear that the Confrontation Clause applies to forensic reports. In Melendez-Diaz v. Massachusetts , state prosecutors
introduced “certificates of analysis” (essentially, affidavits)
stating that lab tests had identified a substance seized from the
defendant as cocaine. 557 U. S., at 308. But the State did not
call as witnesses the analysts who had conducted the tests and
signed the certificates. We held that a “straightforward
application” of Crawford showed a constitutional violation.
557 U. S., at 312. The certificates were testimonial: They had
an “evidentiary purpose,” identical to the one served had the
analysts given “live, in-court testimony.” Id. , at 311. And
the certificates were offered to prove the truth of what they
asserted: that the seized powder was in fact cocaine. See id. , at 310–311. So the defendant had a right to
cross-examine the lab-analyst certifiers. In reaching that
conclusion, we rejected the State’s claim that the results of
so-called “neutral, scientific testing” should be subject to a
different rule. Id. , at 317. We again underscored that the
Confrontation Clause commanded not reliability but one way of
testing it—through cross-examination. See ibid. And we
thought that method might have plenty to do in cases involving
forensic analysis. After all, lab tests are “not uniquely immune
from the risk of manipulation” or mistake. Id. , at 318. The
defendant might have used cross-examination to probe “what tests
the analysts performed,” whether those tests “present[ed] a risk of
error,” and whether the analysts had the right skill set to
“interpret[ ] their results.” Id. , at 320.

															Two years later, the Court relied on Melendez-Diaz to hold that a State could not introduce one
lab analyst’s written findings through the testimony of another. In Bullcoming v. New Mexico , 564
U.S. 647 , 651–652 (2011), an analyst tested the blood-alcohol
level of someone charged with drunk driving, and prepared a
“testimonial certification” reporting that the level was higher
than legal. But by the time the driver’s trial began, that analyst
had been placed on unpaid leave. So the State instead called a
different analyst from the same lab to testify as to what the
certification said. The substitute analyst had similar
qualifications, and knew about the type of test performed. But the
Court held that insufficient to satisfy the Confrontation Clause.
The “surrogate testimony,” the Court explained, “could not convey
what [the certifying analyst] knew or observed” about “the
particular test and testing process he employed.” Id. , at
661. Nor could that “testimony expose any lapses or lies on the
certifying analyst’s part,” or offer any insight into whether his
leave-without-pay was the result of misconduct. Id. , at 662.
Concluded the Court: “[W]hen the State elected to introduce [the]
certification,” its author—and not any substitute—“became [the]
witness [that the defendant] had the right to confront.” Id. , at 663.

															The very next Term brought another case in which
one lab analyst related what another had found—though this time on
the way to stating her own conclusion. In Williams v. Illinois , 567 U.S.
50 (2012), state police sent vaginal swabs from a rape victim
known as L. J. to a private lab for DNA testing. When the lab
sent back a DNA profile, a state analyst checked it against the
police department’s database and found that it matched the profile
of prior arrestee Sandy Williams. The State charged Williams with
the rape, and he went to trial. The prosecution chose not to bring
the private lab analyst to the stand. Instead, it called Sandra
Lambatos, the state analyst who had searched the police database
and found the DNA match. Lambatos had no first-hand knowledge of
how the private lab had produced its results; she did not even know
whether those results actually came from L. J.’s vaginal swabs (as
opposed to some other sample). But she spoke repeatedly about
comparing Williams’s DNA to the DNA “found in [L. J.’s]
vaginal swabs.” Id. , at 61, 71 (plurality opinion); see id. , at 124 (Kagan, J., dissenting). So in addition to
describing how she discovered a match, Lambatos became the conduit
for what a different analyst had reported—that a particular DNA
profile came from L. J.’s vaginal swabs. Williams objected, at
trial and later: He thought that, just as in Bullcoming ,
crucial evidence had been admitted through a surrogate expert, thus
violating his right of confrontation.

															But the Illinois Supreme Court rejected
Williams’s claim, holding that Lambatos’s testimony about the
private lab analyst’s finding did not raise a Confrontation Clause
issue. See People v. Williams , 238 Ill. 2d 125,
143–144, 939 N.E.2d 268, 278–279 (2010). The court explained that
under state evidence law, an expert can disclose “underlying facts
and data” for “the purpose of explaining the basis for [her]
opinion.” Id ., at 137, 143, 939 N. E. 2d, at 274–275,
278. And when she does so, the court held, the testimony is not
subject to the Confrontation Clause because it is not admitted “for
the truth of the matter asserted.” Id ., at 143, 939
N. E. 2d, at 278. Thus, Lambatos could relay the private lab’s
finding that L. J.’s vaginal swabs produced a certain DNA
profile in order to “explain[ ] the basis for her opinion”
that “there was a DNA match between [Williams’s] blood sample and
the semen sample recovered from L. J.” Id. , at 150, 939
N. E. 2d, at 282. The admission of the private lab report’s
contents for that “limited purpose,” the court reasoned, would “aid
the [factfinder] in assessing the value of [Lambatos’s] opinion.” Id. , at 144, 939 N. E. 2d, at 278; see id. , at
150, 939 N. E. 2d, at 282.

															This Court granted Williams’s petition for
certiorari, but failed to produce a majority opinion. Four Members
of the Court approved the Illinois Supreme Court’s approach to
“basis evidence,” and agreed that Lambatos’s recitation of the
private lab’s findings served “the legitimate nonhearsay purpose of
illuminating the expert’s thought process.” Williams , 567
U. S., at 78 (plurality opinion). But the remaining five
Members rejected that view. Those five stated, in two opinions,
that basis evidence is generally introduced for its truth, and was
so introduced at Williams’s trial. Justice Thomas explained that
“the purportedly limited reason for [the basis] testimony—to aid
the factfinder in evaluating the expert’s opinion—necessarily
entail[ed] an evaluation of whether [that] testimony [was] true”:
“[T]he validity of Lambatos’[s] opinion ultimately turned on the
truth of [the private lab analyst’s] statements.” Id. , at
106, n. 1, 108 (concurring in judgment). A dissent for another
four Justices agreed: “[T]he utility of the [private analyst’s]
statement that Lambatos repeated logically depended on its truth.” Id ., at 132 (opinion of Kagan, J.). And the State could not
avoid that conclusion by “rely[ing] on [Lambatos’s] status as an
expert.” Id. , at 126. Those shared views might have made for
a happy majority, except that a different Confrontation Clause
issue intruded. Justice Thomas thought that the private lab report
was not testimonial because it lacked sufficient formality, so
affirmed the Illinois Supreme Court on that alternative ground. The
bottom line was that Williams lost, even though five Members of
this Court rejected the state court’s “not for the truth”
reasoning.[ 1 ]

															Our opinions in Williams “have sown
confusion in courts across the country” about the Confrontation
Clause’s application to expert opinion testimony. Stuart v. Alabama , 586 U. S. ___, ___ (2018) (Gorsuch, J.,
dissenting from denial of certiorari) (slip op., at 2). Some courts
have applied the Williams plurality’s “not for the truth”
reasoning to basis testimony, while others have adopted the opposed
five-Justice view.[ 2 ] This case
emerged out of that muddle.

															B

															Like Melendez-Diaz , this case involves
drugs. In December 2019, Arizona law enforcement officers executed
a search warrant on a property in the foothills of Yuma County.
Inside a shed on the property, they found petitioner Jason Smith.
They also found a large quantity of what appeared to be drugs and
drug-related items. As a result, Smith was charged with possessing
dangerous drugs (methamphetamine) for sale; possessing marijuana
for sale; possessing narcotic drugs (cannabis) for sale; and
possessing drug paraphernalia. He pleaded not guilty, and the case
was set for trial.

															In preparation, the State sent items seized from
the shed to a crime lab run by the Arizona Department of Public
Safety (DPS) for a “full scientific analysis.” App. to Pet. for
Cert. 127a. The State’s request identified Smith as the individual
“associated” with the substances, listed the charges against him,
and noted that “[t]rial ha[d] been set.” Ibid. Analyst
Elizabeth Rast communicated with prosecutors about exactly which
items needed to be examined, and then ran the requested tests. See id. , at 99a.

															Rast prepared a set of typed notes and a signed
report, both on DPS letterhead, about the testing. The notes
documented her lab work and results. They disclosed, for each of
eight items: a “[d]escription” of the item; the weight of the item
and how the weight was measured; the test(s) she performed on the
item, including whether she first ran a “[b]lank” on the testing
equipment; the results of those tests; and a “[c]onclusion” about
the item’s identity. See id ., at 88a–98a. The signed report
then distilled the notes into two pages of ultimate findings,
denoted “results/interpretations.” See id ., at 85a–87a.
After listing the eight items, the report stated that four
“[c]ontained a usable quantity of methamphetamine,” three
“[c]ontained a usable quantity of marijuana,” and one “[c]ontained
a usable quantity of cannabis.” Id ., at 86a–87a. The State
originally planned for Rast to testify about those matters at
Smith’s trial.

															But with three weeks to go, the State called an
audible, replacing Rast with a different DPS analyst as its expert
witness. In the time between testing and trial, Rast had stopped
working at the lab, for unexplained reasons. And the State chose
not to rely on the now-former employee as a witness. So the
prosecutors filed an amendment to their “final pre-trial conference
statement” striking out the name Elizabeth Rast and adding
“Greggory Longoni, forensic scientist (substitute expert).” Id ., at 26a. Longoni had no prior connection to the Smith
case, and the State did not claim otherwise. Its amendment simply
stated that “Mr. Longoni will provide an independent opinion on the
drug testing performed by Elizabeth Rast.” Ibid. And it
continued: “Ms. Rast will not be called. [Mr. Longoni] is expected
to have the same conclusion.” Ibid. And he did come to the same conclusion, in
reliance on Rast’s records. Because he had not participated in the
Smith case, Longoni prepared for trial by reviewing Rast’s report
and notes. And when Longoni took the stand, he referred to those
materials and related what was in them, item by item by item. As to
each, he described the specific “scientific method[s]” Rast had
used to analyze the substance ( e.g. , a microscopic
examination, a chemical color test, a gas chromatograph/mass
spectrometer test). Id. , at 41a; see id ., at 42a,
46a–48a. And as to each, he stated that the testing had adhered to
“general principles of chemistry,” as well as to the lab’s
“policies and practices,” id ., at 47a–48a; see id .,
at 40a; so he noted, for example, that Rast had run a “blank” to
confirm that testing equipment was not contaminated, id. , at
42a, 47a. After thus telling the jury what Rast’s records conveyed
about her testing of the items, Longoni offered an “independent
opinion” of their identity. Id. , at 46a–47a, 49a. More
specifically, the opinions he offered were: that Item 26 was “a
usable quantity of marijuana,” that Items 20A and 20B were “usable
quantit[ies] of methamphetamine,” and that Item 28 was “[a] usable
quantity of cannabis.” Ibid. After Smith was convicted, he brought an appeal
focusing on Longoni’s testimony. In Smith’s view, the State’s use
of a “substitute expert”—who had not participated in any of the
relevant testing—violated his Confrontation Clause rights. Id. , at 26a; see Brief for Appellant Smith in No. 1 CA–CR
21–0451 (Ariz. Ct. App.), pp. 20–23. The real witness against
him, Smith urged, was Rast, through her written statements; but he
had not had the opportunity to cross-examine her. See ibid. The State disagreed. In its view, Longoni testified about “his own
independent opinions,” even though making use of Rast’s records.
Brief for Appellee Arizona in No. 1 CA–CR 21–0451 (Ariz. Ct. App.),
p. 22. So Longoni was the only witness Smith had a right to
confront. See ibid. The Arizona Court of Appeals affirmed Smith’s
convictions, rejecting his Confrontation Clause challenge. It
relied on Arizona precedent (similar to the Illinois Supreme
Court’s decision in Williams ) stating that an expert may
testify to “the substance of a non-testifying expert’s analysis, if
such evidence forms the basis of the [testifying] expert’s
opinion.” App. to Pet. for Cert. 11a–12a (quoting State
ex rel. Montgomery v. Karp , 236 Ariz. 120, 124, 336
P.3d 753, 757 (App. 2014)). That is because, the Arizona courts
have said, the “underlying facts” are then “used only to show the
basis of [the in-court witness’s] opinion and not to prove their
truth.” Ibid. , 336 P. 3d, at 757. On that view, the
Court of Appeals held, Longoni could constitutionally
“present[ ] his independent expert opinions” as “based on his
review of Rast’s work.” App. to Pet. for Cert. 11a.

															We granted certiorari to consider that
reasoning, 600 U. S. ___ (2023), and we now reject
it.[ 3 ]

															II

															Smith’s confrontation claim can succeed only
if Rast’s statements came into evidence for their truth. As earlier
explained, the Clause applies solely to “testimonial hearsay .” Davis , 547 U. S., at 823 (emphasis
added); see supra , at 3. And that means the Clause “does not
bar the use of testimonial statements for purposes other than
establishing the truth of the matter asserted.” Crawford ,
541 U. S., at 60, n. 9. So a court analyzing a
confrontation claim must identify the role that a given
out-of-court statement—here, Rast’s statements about her lab
work—served at trial. On that much, indeed, the entire Williams Court agreed. Amid all the fracturing that case
produced, every Justice defined its primary question in the same
way: whether the absent analyst’s statements were introduced for
their truth. See 567 U. S., at 57–58 (plurality opinion); id. , at 104 (Thomas, J., concurring in judgment); id. , at 125–126 (Kagan, J., dissenting). The parties here
likewise concur in that framing. See Brief for Smith 28–29; Brief
for Arizona 17–18. If Rast’s statements came in to establish the
truth of what she said, then the Clause’s alarms begin to ring; but
if her statements came in for another purpose, then those alarms
fall quiet.

															Where the parties disagree, of course, is in
answering that purpose question. Smith argues that the “for the
truth” condition is satisfied here, just as much as in Melendez-Diaz or Bullcoming . See Brief for Smith
23–28; supra , at 3–5. In his view, Rast’s statements were
conveyed, via Longoni’s testimony, to establish that what she said
happened in the lab did in fact happen. Or put more specifically,
those statements were conveyed to show that she used certain
standard procedures to run certain tests, which enabled
identification of the seized items. The State sees the matter
differently. See Brief for Arizona 19–26. Echoing the Arizona Court
of Appeals (and the Illinois Supreme Court in Williams ), the
State argues that Rast’s statements came into evidence not for
their truth, but instead to “show the basis” of the in-court
expert’s independent opinion. Brief for Arizona 21; see supra , at 6. And to defend that characterization, Arizona
emphasizes that its Rule of Evidence 703 (again, like Illinois’s)
authorizes the admission of such statements only for that
purpose— i.e. , to “help[ ] the jury [to] evaluate” the
opinion testimony. Brief for Arizona 20–21; see post , at 8
(Alito, J., concurring in judgment) (arguing the same as to Federal
Rule of Evidence 703).

															Evidentiary rules, though, do not control the
inquiry into whether a statement is admitted for its truth. That
inquiry, as just described, marks the scope of a federal
constitutional right. See supra , at 11. And federal
constitutional rights are not typically defined—expanded or
contracted—by reference to non-constitutional bodies of law like
evidence rules.[ 4 ] The
confrontation right is no different, as Crawford made clear.
“Where testimonial statements are involved,” that Court explained,
“the Framers [did not mean] to leave the Sixth Amendment’s
protection to the vagaries of the rules of evidence.” 541
U. S., at 61. Justice Thomas reiterated the point in Williams : “[C]oncepts central to the application of the
Confrontation Clause are ultimately matters of federal
constitutional law that are not dictated by state or federal
evidentiary rules.” 567 U. S., at 105 (opinion concurring in
judgment). We therefore do not “accept [a State’s] nonhearsay label
at face value.” Id. , at 106; see id. , at 132 (Kagan,
J., dissenting). Instead, we conduct an independent analysis of
whether an out-of-court statement was admitted for its truth, and
therefore may have compromised a defendant’s right of
confrontation.

															We did just that in Tennessee v. Street —and in so doing showcased how an out-of-court
statement can come into evidence for a non-truth-related reason.
See 471 U. S., at 410–417. Street was charged with murder,
based mostly on a stationhouse confession. At trial, he claimed
that the confession was coerced, and in a peculiar way: The
sheriff, he said, had read aloud an accomplice’s confession and
forced him to repeat it. On rebuttal, the State introduced the
other confession (through the sheriff ’s testimony) to
demonstrate to the jury all the ways its content deviated from
Street’s. We upheld that use as “nonhearsay.” Id. , at 413.
The other confession came in, we explained, not to prove “the truth
of [the accomplice’s] assertions” about how the murder happened,
but only to disprove Street’s claim about how the sheriff elicited
his own confession. Ibid. Or otherwise said, the point was
to show, by highlighting the two confessions’ differences, that
Street’s was not a “coerced imitation.” Id. , at 414. For
that purpose, the truth of the accomplice’s confession (and the
credibility of the accomplice himself ) was irrelevant.

															But truth is everything when it comes to the
kind of basis testimony presented here. If an expert for the
prosecution conveys an out-of-court statement in support of his
opinion, and the statement supports that opinion only if true, then
the statement has been offered for the truth of what it asserts.
How could it be otherwise? “The whole point” of the prosecutor’s
eliciting such a statement is “to establish— because of the
[statement’s] truth —a basis for the jury to credit the
testifying expert’s” opinion. Stuart , 586 U. S., at ___
(Gorsuch, J., dissenting from denial of certiorari) (slip op., at
3) (emphasis in original). Or said a bit differently, the truth of
the basis testimony is what makes it useful to the prosecutor; that
is what supplies the predicate for—and thus gives value to—the
state expert’s opinion. So “[t]here is no meaningful distinction
between disclosing an out-of-court statement” to “explain the basis
of an expert’s opinion” and “disclosing that statement for its
truth.” Williams , 567 U. S., at 106 (Thomas, J.,
concurring in judgment). A State may use only the former label, but
in all respects the two purposes merge.

															Or to see the point another way, consider it
from the factfinder’s perspective. In the view of the Arizona
courts, an expert’s conveyance of another analyst’s report enables
the factfinder to “determine whether [the expert’s] opinion should
be found credible.” Karp , 236 Ariz., at 124, 336 P. 3d,
at 757; see Williams , 238 Ill. 2d, at 144, 939 N. E.
2d, at 278 (also stating that such a report “aid[s] the jury in
assessing the value of [the expert’s] opinion”); supra , at
6, 10. That is no doubt right. The jury cannot decide whether the
expert’s opinion is credible without evaluating the truth of the
factual assertions on which it is based. See D. Kaye, D. Bernstein,
A. Ferguson, M. Wittlin, & J. Mnookin, The New Wigmore: Expert
Evidence §5.4.1, p. 271 (3d ed. 2021). If believed true, that basis
evidence will lead the jury to credit the opinion; if believed
false, it will do the opposite. See Williams , 567
U. S., at 106, and n. 1 (Thomas, J., concurring in
judgment); id. , at 126–127 (Kagan, J., dissenting). But that
very fact is what raises the Confrontation Clause problem. For the
defendant has no opportunity to challenge the veracity of the
out-of-court assertions that are doing much of the work.

															And if that explanation seems a bit abstract,
then take this case as its almost-too-perfect illustration. Recall
that Rast tested eight seized items before she disappeared from the
scene. At trial, the prosecutor asked the State’s “substitute
expert” Longoni to testify about four of them (with the rest
dropping out of the case). App. to Pet. for Cert. 26a. A recap of
their exchange about one item will be enough; the rest followed the
same pattern. Remember as you read that Longoni, though familiar
with the lab’s general practices, had no personal knowledge about
Rast’s testing of the seized items. Rather, as his testimony makes
clear, what he knew on that score came only from reviewing Rast’s
records. With that as background:

															Q Turn your attention to Item 26. I’m going to
hand you what’s been marked as State’s Exhibit 98 [Rast’s
notes]. . . . Did you review how [Item] 26 was
tested in this case?

															A Yes.

															Q When you reviewed it, did you notice whether
the [standard lab] policies and practices that you have just
described were followed?

															A Yes.

															Q Were they followed?

															A Yes.

															.     .     .     .     .

															Q From your review of the lab notes in this
case, can you tell me what scientific method was used to analyze
Item 26?

															A Yes.

															Q And what was used?

															A The microscopic examination and the chemical
color test. . . .

															Q That was done in this case?

															A Yes, it was.

															Q Was there a blank done to prevent
contamination, make sure everything was clean?

															A According to the notes, yes.

															.     .     .     .     .

															Q In reviewing what was done, your knowledge
and training as a forensic scientist, your knowledge and experience
with DPS’s policies, practices, procedures, your knowledge of
chemistry, the lab notes, the intake records, the chemicals used,
the tests done, can you form an independent opinion on the identity
of Item 26?

															A Yes.

															Q What is that opinion?

															A That is a usable quantity of marijuana. Id ., at 39a–42a, 46a. And then the
prosecutor went on to Items 20A, 20B, and 28, asking similar
questions, receiving similar answers based on Rast’s records, and
finally eliciting similar “independent opinions”—which were no more
than what Rast herself had concluded. See supra , at 8–9.
“Yes,” Longoni confirmed, just as Item 26 was a “usable quantity of
marijuana,” Items 20A and 20B were “usable quantit[ies] of
methamphetamine” and Item 28 was a “usable quantity of cannabis.”
App. to Pet. for Cert. 46a, 47a, 49a.

															Rast’s statements thus came in for their truth,
and no less because they were admitted to show the basis of
Longoni’s expert opinions. All those opinions were predicated on
the truth of Rast’s factual statements. Longoni could opine that
the tested substances were marijuana, methamphetamine, and cannabis
only because he accepted the truth of what Rast had reported about
her work in the lab—that she had performed certain tests according
to certain protocols and gotten certain results. And likewise, the
jury could credit Longoni’s opinions identifying the substances
only because it too accepted the truth of what Rast reported about
her lab work (as conveyed by Longoni). If Rast had lied about all
those matters, Longoni’s expert opinion would have counted for
nothing, and the jury would have been in no position to convict. So
the State’s basis evidence—more precisely, the truth of the
statements on which its expert relied—propped up its whole case.
But the maker of those statements was not in the courtroom, and
Smith could not ask her any questions.

															Approving that practice would make our decisions
in Melendez-Diaz and Bullcoming a dead letter, and
allow for easy evasion of the Confrontation Clause. As earlier
described, those two decisions applied Crawford in
“straightforward” fashion to forensic evidence. Melendez-Diaz , 557 U. S., at 312; see Bullcoming , 564 U. S., at 659–661; supra , at
3–5. The first prevented the introduction of a lab analyst’s
testimonial report sans lab analyst. The second refused to accede
to the idea that any old analyst— i.e. , a substitute who had
not taken part in the lab work—would do. Arizona offers only a
slight variation. On its view, a surrogate analyst can testify to
all the same substance—that is, someone else’s substance—as long as
he bases an “independent opinion” on that material. And that is
true even if, as here, the proffered opinion merely replicates,
rather than somehow builds on, the testing analyst’s conclusions.
So every testimonial lab report could come into evidence through
any trained surrogate, however remote from the case. And no
defendant would have a right to cross-examine the testing analyst
about what she did and how she did it and whether her results
should be trusted. In short, Arizona wants to end run all we have
held the Confrontation Clause to require. It cannot.

															Properly understood, the Clause still allows
forensic experts like Longoni to play a useful role in criminal
trials. Because Longoni worked in the same lab as Rast, he could
testify from personal knowledge about how that lab typically
functioned—the standards, practices, and procedures it used to test
seized substances, as well as the way it maintained chains of
custody. (Indeed, Longoni did just that in a different part of his
testimony. See App. to Pet. for Cert. 32a–39a.) Or had he not been
familiar with Rast’s lab, he could have testified in general terms
about forensic guidelines and techniques—perhaps explaining what it
means for a lab to be accredited and what requirements
accreditation imposes. Or as the Williams plurality and
dissent both observed, he might have been asked—and could have
answered—any number of hypothetical questions, taking the form of:
“ If or assuming some out-of-court statement were
true, what would follow from it?” See 567 U. S., at 67–68; id. , at 129, n. 2. (The State of course would then have
to separately prove the thing assumed.) The United States,
appearing as amicus curiae in support of neither party,
usefully addressed these matters at oral argument, distinguishing
Longoni’s testimony as block-quoted above from the various kinds of
testimony just described. See Tr. of Oral Arg. 36–41. The latter
forms of testimony allow forensic expertise to inform a criminal
case without violating the defendant’s right of confrontation. And
we offer these merely as examples; there may be others.

															But as the United States acknowledged, the bulk
of Longoni’s testimony took no such permissible form. Ibid. Here, the State used Longoni to relay what Rast wrote down about
how she identified the seized substances. Longoni thus effectively
became Rast’s mouthpiece. He testified to the precautions (she
said) she took, the standards (she said) she followed, the tests
(she said) she performed, and the results (she said) she obtained.
The State offered up that evidence so the jury would believe it—in
other words, for its truth. So if the out-of-court statements were
also testimonial, their admission violated the Confrontation
Clause. Smith would then have had a right to confront the person
who actually did the lab work, not a surrogate merely reading from
her records.

															III

															What remains is whether the out-of-court
statements Longoni conveyed were testimonial. As earlier explained,
that question is independent of everything said above: To implicate
the Confrontation Clause, a statement must be hearsay (“for the
truth”) and it must be testimonial—and those two issues are
separate from each other. See supra , at 3. The latter, this
Court has stated, focuses on the “primary purpose” of the
statement, and in particular on how it relates to a future criminal
proceeding. See ibid. (noting varied formulations of the
standard).[ 5 ] A court must
therefore identify the out-of-court statement introduced, and must
determine, given all the “relevant circumstances,” the principal
reason it was made. Bryant , 562 U. S., at 369.

															But that issue is not now fit for our
resolution. The question presented in Smith’s petition for
certiorari did not ask whether Rast’s out-of-court statements were
testimonial. See supra , at 11, n. 3 (quoting Pet. for
Cert. i). Instead, it took as a given that they were. See id ., at i. That presentation reflected the Arizona Court of
Appeals’ opinion. As described earlier, that court relied on the
“not for the truth” rationale we have just rejected. See supra , at 10. It did not decide whether Rast’s statements
were testimonial. Nor, to our knowledge, did the trial court ever
take a stance on that issue. Because “we are a court of review, not
of first view,” we will not be the pioneer court to decide the
matter. Cutter v. Wilkinson , 544
U.S. 709 , 718, n. 7 (2005). And indeed, we are not sure if
there remains a matter to decide. Smith argues that the State has
forfeited the argument: Arizona, he says, “gave no hint in the
proceedings below that it believed Rast’s statements were anything
but testimonial.” Reply Brief 3. The State denies that assertion,
pointing to a passage about Williams in its lower court
briefing. See Brief for Arizona 39, n. 14. The dispute is best
addressed by a state court. So we return the testimonial issue,
including the threshold forfeiture matter, to the Arizona Court of
Appeals.

															But we offer a few thoughts, based on the
arguments made here, about the questions the state court might
usefully address if the testimonial issue remains live. First, the
court will need to consider exactly which of Rast’s statements are
at issue. In this Court, the parties disputed whether Longoni was
reciting from Rast’s notes alone, or from both her notes and final
report. See supra , at 8–9 (describing those documents). In
Arizona’s view, everything Longoni testified to came from Rast’s
notes; although he at times used the word “report,” a close
comparison of the documents and his testimony reveals (the State
says) that he meant only the notes. See Brief for Arizona 39–40;
Tr. of Oral Arg. 69–72; see also App. to Pet. for Cert. 39a–40a,
48a. Smith disagrees, taking Longoni’s references to the “report,”
as well as the notes, at face value. According to Smith, Longoni
“relied on both” documents and in fact “treated them as a unit,”
with the notes “attached” to the report as “essentially an
appendix.” Reply Brief 4; Tr. of Oral Arg. 25, 98. Resolving that
dispute might, or then again might not, affect the court’s ultimate
disposition of Smith’s Confrontation Clause claim. We note only
that before the court can decide the primary purpose of the
out-of-court statements introduced at Smith’s trial, it needs to
determine exactly what those statements were.

															In then addressing the statements’ primary
purpose—why Rast created the report or notes—the court should
consider the range of recordkeeping activities that lab analysts
engage in. See generally supra , at 3 (describing
formulations of the testimonial inquiry). After all, some records
of lab analysts will not have an evidentiary purpose. The United
States as amicus curiae notes, for example, that lab records
may come into being primarily to comply with laboratory
accreditation requirements or to facilitate internal review and
quality control. See Tr. of Oral Arg. 51. Or some analysts’ notes
may be written simply as reminders to self. See id. , at 20,
52. In those cases, the record would not count as testimonial. To
do so, the document’s primary purpose must have “a focus on court.” Id ., at 52. And again, the state court on remand should make
that assessment as to each record whose substance Longoni
conveyed.

															IV

															Our holding today follows from all this Court
has held about the Confrontation Clause’s application to forensic
evidence. A State may not introduce the testimonial out-of-court
statements of a forensic analyst at trial, unless she is
unavailable and the defendant has had a prior chance to
cross-examine her. See Crawford , 541 U. S., at 68; Melendez-Diaz , 557 U. S., at 311. Neither may the State
introduce those statements through a surrogate analyst who did not
participate in their creation. See Bullcoming , 564
U. S., at 663. And nothing changes if the surrogate—as in this
case—presents the out-of-court statements as the basis for his
expert opinion. Those statements, as we have explained, come into
evidence for their truth—because only if true can they provide a
reason to credit the substitute expert. So a defendant has the
right to cross-examine the person who made them.

															That means Arizona does not escape the
Confrontation Clause just because Rast’s records came in to explain
the basis of Longoni’s opinion. The Arizona Court of Appeals
thought otherwise, and so we vacate its judgment. To address the
additional issue of whether Rast’s records were testimonial
(including whether that issue was forfeited), we remand the case
for further proceedings not inconsistent with this opinion.

															It is so ordered. Notes 1 The Court also failed to
reach agreement on the testimonial issue. The four Justices who
accepted the state court’s “not for the truth” view also concluded
that the report was not testimonial. See Williams , 567
U. S., at 81–86 (plurality opinion). But they did so for
reasons different from Justice Thomas’s. Compare ibid. with id ., at 110–117 (opinion concurring in judgment). The result
was that no single rationale for affirmance garnered a
majority. 2 Compare, e.g. , State v. Mercier , 2014 ME 28, ¶¶12–14, 87 A.3d 700,
704 (accepting the “not for the truth” rationale for admitting an
expert’s basis testimony); State v. Hutchison , 482
S.W.3d 893, 914 (Tenn. 2016); United States v. Murray , 540 Fed. Appx. 918, 921 (CA11 2013), with People v. Sanchez , 63 Cal. 4th 665, 684, 374 P.3d
320, 333 (2016) (rejecting the “not for the truth” rationale for
admitting an expert’s basis testimony); Martin v. State , 60 A.3d 1100, 1107 (Del. 2013); Young v. United States , 63 A.3d 1033, 1045 (D. C. 2013); Leidig v. State , 475 Md. 181, 234, n. 23, 256
A.3d 870, 901, n. 23 (2021); Commonwealth v. Jones , 472 Mass. 707, 714, 37 N. E. 3d 589, 597
(2015). 3 The question on which we
granted certiorari made reference as well to another aspect of the
Court of Appeals’ reasoning. That question asks whether the
Confrontation Clause permits “testimony by a substitute expert
conveying the testimonial statements of a nontestifying forensic
analyst, on the grounds that (a) the testifying expert offers some
independent opinion and the analyst’s statements are offered not
for their truth but to explain the expert’s opinion, and (b) the
defendant did not independently seek to subpoena the analyst.” Pet.
for Cert. i. The “(b)” in that question arises from the following
sentence in the court’s opinion: “Had Smith sought to challenge
Rast’s analysis, he could have called her to the stand and
questioned her, but he chose not to do so.” App. to Pet. for Cert.
12a. We need not spend much time on that rationale because the
State rightly does not defend it. As we held in Melendez-Diaz , a defendant’s “ability to subpoena” an absent
analyst “is no substitute for the right of confrontation.” 557
U. S., at 324. The Confrontation Clause “imposes a burden on
the prosecution to present its witnesses, not on the defendant to
bring those adverse witnesses into court.” Ibid. 4 One qualification is
appropriate. If an evidentiary rule reflects a long-established
understanding, then it might shed light on the historical meaning
of the Confrontation Clause. But that could not possibly be said of
Rule 703—the rule Arizona cites to support the introduction of
basis evidence. On the contrary, that rule is a product of the
late-20th century, and was understood from the start to depart from
past practice. See Brief for Richard D. Friedman as Amicus
Curiae 17; Advisory Committee’s Notes on Fed. Rule Evid. 703,
28 U. S. C. App., p. 393. 5 Given that focus, the
mine-run of materials on which most expert witnesses rely in
forming opinions—including books and journals, surveys, and
economic or scientific studies—will raise no serious confrontation
issues. See Brief for United States as Amicus Curiae 13–17
(giving examples of classic expert-basis evidence). That is because
the preparation of those materials generally lacks any “evidentiary
purpose.” Melendez-Diaz , 557 U. S., at
311. SUPREME COURT OF THE UNITED STATES

															_________________

															No. 22–899

															_________________

															JASON SMITH, PETITIONER v. ARIZONA

															on writ of certiorari to the court of appeals
of arizona, division one

															[June 21, 2024]

															Justice Thomas, concurring in part.

															I join the Court in all but Part III of its
opinion. The Sixth Amendment’s Confrontation Clause provides: “In
all criminal prosecutions, the accused shall enjoy the right
. . . to be confronted with the witnesses against him.”
This Clause bars the admission of an absent witness’s testimonial
statements for their truth, unless the witness is unavailable and
the defendant previously had an opportunity to cross-examine that
witness. See Crawford v. Washington , 541 U.S.
36 , 50–56, 60, n. 9 (2004). Today, the Court correctly
concludes that “[w]hen an expert conveys an absent analyst’s
statements in support of his opinion, and the statements provide
that support only if true, then the statements come into evidence
for their truth.” Ante , at 2; see also Williams v. Illinois , 567 U.S.
50 , 106 (2012) (Thomas, J., concurring in judgment). But, a
question remains whether that analyst’s statements were
testimonial. I agree with the Court that, because the courts below
did not consider this question, we should remand for the Arizona
Court of Appeals to answer it in the first instance. Ante ,
at 19–20. But, I disagree with the Court’s suggestion that the
Arizona Court of Appeals should answer that question by looking to
each statement’s “primary purpose.” Ante , at 20–21.

															I continue to adhere to my view that “the
Confrontation Clause is implicated by extrajudicial statements only
insofar as they are contained in formalized testimonial materials,
such as affidavits, depositions, prior testimony, or
confessions.” [ 1 ]* White v. Illinois , 502 U.S.
346 , 365 (1992) (Thomas, J., concurring in part and concurring
in judgment); see also Ohio v. Clark , 576 U.S.
237 , 254–255 (2015) (Thomas, J., concurring in judgment); Williams , 567 U. S., at 110–111 (opinion of Thomas,
J.); Michigan v. Bryant , 562
U.S. 344 , 379 (2011) (Thomas, J., concurring in judgment); Melendez-Diaz v. Massachusetts , 557 U.S.
305 , 329 (2009) (Thomas, J., concurring); Giles v. California , 554 U.S.
353 , 377–378 (2008) (Thomas, J., concurring); Davis v. Washington , 547 U.S.
813 , 837 (2006) (opinion of Thomas, J.); Lilly v. Virginia , 527 U.S.
116 , 143 (1999) (Thomas, J., concurring in part and concurring
in judgment). The Confrontation Clause guarantees a criminal
defendant “the right . . . to be confronted with the
witnesses against him.” Amdt. 6. As I have previously explained,
“[w]itnesses . . . are those who bear testimony. And
testimony is a solemn declaration or affirmation made for the
purpose of establishing or proving some fact.” Davis , 547
U. S., at 836 (opinion of Thomas, J.) (citation, internal
quotation marks, and alterations omitted). This understanding is
grounded in “[t]he history surrounding the right to confrontation,”
which “was developed to target particular practices that occurred
under the English bail and committal statutes passed during the
reign of Queen Mary, namely, the civil-law mode of criminal
procedure, and particularly its use of ex parte examinations as evidence against the accused.” Id. , at 835
(internal quotation marks omitted). Rather than attempt to divine a
statement’s “primary purpose,” I would look for whether the
statement is “similar in solemnity to the Marian examination
practices that the Confrontation Clause was designed to prevent.” Williams , 567 U. S., at 112 (opinion of Thomas, J.). In
my view, the Arizona Court of Appeals should consider on remand
whether the statements at issue have the requisite formality and
solemnity to qualify as testimonial. If they do not, the
Confrontation Clause poses no barrier to their admission. Notes 1 *The Confrontation Clause “also
reaches the use of technically informal statements when used to
evade the formalized process .” Davis v. Washington , 547 U.S.
813 , 838 (2006) (Thomas, J., concurring in judgment in part and
dissenting in part). SUPREME COURT OF THE UNITED STATES

															_________________

															No. 22–899

															_________________

															JASON SMITH, PETITIONER v. ARIZONA

															on writ of certiorari to the court of appeals
of arizona, division one

															[June 21, 2024]

															Justice Gorsuch, concurring in part.

															I am pleased to join the Court’s opinion holding
that, when an expert presents another’s statements as the “basis”
for his own opinion, he is offering those statements for their
truth. See Parts I, II, and IV, ante .

															I cannot join, however, the Court’s discussion
in Part III about when an absent analyst’s statement might qualify
as “testimonial.” See ante , at 19–21. As the Court says,
“that issue is not now fit for our resolution.” Ante , at 19.
It was not part of the question presented for our review, nor was
it the focus of the decision below. Ante , at 19–20 . In fact, the State devoted so little attention to the “testimonial”
issue in the Arizona courts that any argument it might make on the
subject on remand may be forfeited. Ante , at 20. Further,
the Court’s thoughts on the subject are in no way necessary to the
resolution of today’s dispute. What makes a statement testimonial,
the Court notes, is an entirely “separate” issue. Ante , at
19.

															Nor am I entirely sure about the guidance found
in Part III. The Sixth Amendment protects the accused’s “right
. . . to be confronted with the witnesses against him.”
As the Court sees it, whether a statement being offered for its
truth and tendency to inculpate a defendant triggers that right
depends “on the ‘primary purpose’ of the statement, and in
particular on how it relates to a future criminal proceeding.” Ante , at 19 . I cannot help but wonder whether that is
correct.

															Just consider a few other possibilities. In
protecting the right to confront “witnesses,” perhaps the Sixth
Amendment reaches any “person who gives or furnishes evidence.” United States v. Hubbell , 530 U.S.
27 , 49–50 (2000) (Thomas, J., concurring) (discussing
founding-era meaning of the word “witness” in the Fifth Amendment);
see also id ., at 50, n. 1. Or perhaps the Amendment
reaches all “those who ‘bear testimony.’ ” Crawford v. Washington , 541 U.S.
36 , 51 (2004) (quoting 2 N. Webster, An American Dictionary of
the English Language (1828)). Perhaps, too, a statement “bears
testimony” so long as it “explicitly or implicitly . . .
relate[s] a factual assertion or disclose[s] information.” Doe v. United States , 487 U.S.
201 , 210 (1988) (discussing what makes a statement
“testimonial” for purposes of the Fifth Amendment); see also 2
Webster, An American Dictionary (observing near the founding that
“testimony” could mean “evidence” and “proof of some fact” as well
as a “solemn declaration or affirmation” made to “establis[h] or
prov[e] some fact”). To my mind, all these questions (and maybe
others too) warrant careful exploration in a case that presents
them and, without more assurance, I worry that the Court’s proposed
“primary purpose” test may be a limitation of our own creation on
the confrontation right.

															I am concerned, as well, about the confusion a
“primary purpose” test may engender. Does it focus, for example, on
the purposes an objective observer would assign to a challenged
statement, see ante , at 3 (referencing the “ ‘objective
witness’ ”), the declarant’s purposes in making it, see ante , at 21 (asking “why Rast created the report or notes”),
the government’s purposes in “ ‘procur[ing]’ ” it, see ante , at 3, or maybe still some other point of reference?
Even after we figure out a statement’s purposes, how do we pick the
primary one out of the several a statement might serve? Or
determine in exactly what way that purpose must “relat[e] to a
future criminal proceeding”? Ante , at 19. And if we fail to
find some foothold in text and historical practice for resolving
these questions, how can judges answer them without resort to their
own notions of what would be best?

															Some time ago, Chief Justice Marshall charged
the judiciary with “be[ing] watchful of every inroad” on the
accused’s right to be confronted with the witnesses against him. United States v. Burr , 25 F. Cas. 187, 193 (No.
14,694) (CC Va. 1807). With that cautionary note in mind, I
respectfully concur in all but Part III of the Court’s opinion. SUPREME COURT OF THE UNITED STATES

															_________________

															No. 22–899

															_________________

															JASON SMITH, PETITIONER v. ARIZONA

															on writ of certiorari to the court of appeals
of arizona, division one

															[June 21, 2024]

															Justice Alito, with whom the Chief Justice
joins, concurring in the judgment.

															Today, the Court inflicts a needless,
unwarranted, and crippling wound on modern evidence law. There was
a time when expert witnesses were required to express their
opinions as responses to hypothetical questions. But eventually,
this highly artificial, awkward, confusing, and abuse-laden form of
testimony earned virtually unanimous condemnation. More than a
century ago, judges, evidence scholars, and legal reform
associations began to recommend that courts abandon the required
use of hypotheticals, and more than 50 years ago, the Federal Rules
of Evidence did so. Now, however, the Court proclaims that a
prosecution expert will frequently violate the Confrontation Clause
when he testifies in strict compliance with the Federal Rules of
Evidence and similar modern state rules. Instead, the Court
suggests that such experts revert to the form that was buried a
half-century ago. Ante, at 18. There is no good reason for
this radical change.

															I

															To explain why I think the Court has gone far
astray, I begin with a brief look at the history of expert
testimony—and particularly, why the hypothetical-question
requirement was replaced by the (superior) mode of testimony
allowed by the Federal Rules of Evidence.

															A

															Expert testimony presents a challenge for a
legal system like ours that restricts a fact-finder’s ability to
consider hearsay. This is so because an expert’s opinion very often
is based on facts that are not proved in court. As a modern
treatise puts it, the value of experts lies in their ability to
“brin[g] to bear a body of knowledge largely extraneous to the
facts of the particular case.” D. Kaye, D. Bernstein, A. Ferguson,
M. Wittlin, & J. Mnookin, The New Wigmore: Expert Evidence
§1.2.1, p. 4 (3d ed. 2021) (Kaye). Wigmore made the same point when
he wrote that “[n]o one professional man can know from personal
observation more than a minute fraction of the data which he must
every day treat as working truths.” 1 J. Wigmore, Evidence §665(3),
p. 762 (1904) (Wigmore). Instead, experts routinely “rel[y] on the
reported data of fellow-scientists, learned by perusing their
reports in books and journals.” Id ., at 762–763 (emphasis
deleted); see also Kaye §4.1, at 165 (“[P]art of an expert’s very
expertise inevitably derive[s] from hearsay”).

															Despite this problem, courts in Great Britain
and this country long ago recognized the value of expert testimony
and concluded that they “must . . . accept this kind of
knowledge from scientific men,” even if it meant allowing testimony
based on facts of which the expert did not have firsthand
knowledge. See 1 Wigmore 763; 1 S. Greenleaf, Evidence §430(l), p.
529 (rev. 16th ed. 1899) (“It would be absurd to deny judicial
standing to such knowledge, because all scientific data must be
handed down from generation to generation by hearsay, and each
student can hope to test only a trifling fraction of scientific
truth by personal experience”); Slocovich v. Orient Mut.
Ins. Co. , 108 N.Y. 56, 64, 14 N.E. 802, 805 (1888) (“An expert
is qualified to give evidence as to things which he has never seen.
He may base an opinion upon facts proved by other witnesses, or
upon facts assumed and embraced within the case”).

															Recognizing this reality, a court in the
late-18th century admitted expert testimony about the seaworthiness
of a ship based on a survey conducted when the expert was not
present. Thornton v. Royal Exchange Assurance Co. ,
Peake 37, 38, 170 Eng. Rep. 70, 71 (N. P. 1790). Similarly, an
early-19th century decision allowed ship surveyors to testify to
the seaworthiness of a vessel they had never seen. Beckwith v. Sydebotham , 1 Camp. 116, 170 Eng. Rep. 897 (N. P. 1807).
The opposing party objected that the experts did not know the
underlying facts to be true, but the court admitted their opinions
because the experts’ technical knowledge could assist the jury. Ibid. The fact that “the truth of the facts stated to them
was not certainly known” went to the weight of the testimony, not
its admissibility. Ibid. Throughout the 19th and into the 20th century,
experts generally testified in the form of an opinion in response
to a hypothetical question. An attorney would ask an expert to
assume that certain facts were true and would then query whether a
particular conclusion could conceivably follow. See 3 S. Saltzburg,
M. Martin, D. Capra, & J. Berch, Federal Rules of Evidence
Manual §703.02[1] (13th ed. 2023).

															This procedure was highly artificial because it
bore little resemblance to the way in which experts actually form
opinions. And the procedure surely did not conform to the way lay
jurors think and speak.

															The procedure’s aim was to prevent a jury from
jumping to the conclusion that the facts packed into the
hypothetical were true, but it is questionable whether the practice
achieved that objective. For instance, here is the question that
defense counsel asked a psychiatric witness in Charles Guiteau’s
trial for murdering President Garfield:

															“Q. . . . Assume it to be a fact
that there was a strong hereditary taint of insanity in the blood
of the prisoner at the bar; also that at about the age of
thirty-five years his mind was so much deranged that he was a fit
subject to be sent to an insane asylum; also that at different
times from that date during the next succeeding five years he
manifested such decided symptoms of insanity, without stimulation,
that many different persons conversing with him and observing his
conduct believed him to be insane; also that during the month of
June, 1881, at about the expiration of said term of five years, he
honestly became dominated by the idea that he was inspired of God
to remove by death the President of the United States; also that he
acted upon what he believed to be such inspiration, and what he
believed to be in accordance with the Divine will, in preparation
for and in the accomplishment of such purpose; also that he
committed the act of shooting the President under what he believed
to be a Divine command which he was not at liberty to disobey, and
which belief amounted to a conviction that controlled his
conscience and over-powered his will as to that act, so that he
could not resist the mental pressure upon him; also that
immediately after the shooting he appeared calm and as one relieved
by the performance of a great duty; also that there was no other
adequate motive for the act than the conviction that he was
executing the Divine will for the good of his country—assuming all
these propositions to be true, state whether in your opinion the
prisoner was sane or insane at the time of shooting President
Garfield?

															“A. Assuming those to be true, I should say the
prisoner was insane.” C. Rosenberg, The Trial of the Assassin
Guiteau 144–145 (1968) (Rosenberg).

															How likely is it that a jury hearing a question
like that would keep in mind that all the facts loaded into the
question were merely hypothetical and not necessarily supported by
the evidence in the case?

															The Guiteau example illustrates many other
problems with hypothetical questioning. For one, hypothetical
questions were “difficult for the attorneys to frame, for the court
to rule on, and for the jury to understand.” M. Ladd, Expert
Testimony, 5 Vand. L. Rev. 414, 425 (1952) (Ladd). Like the
question above, the hypotheticals were often “so built up and
contrived” that they were impossible for either the jury or the
expert to follow. 1 J. Wigmore, Evidence 1095 (2d ed. 1923) (1
Wigmore 2d); accord, Ladd 427. One case involved a hypothetical
that extended over “eighty-three pages of typewritten transcript,
and an objection involved in fourteen pages more of the record.” Treadwell v. Nickel , 194 Cal. 243, 266, 228 P. 25, 35
(1924). Such questions required an expert to have the extraordinary
ability “to comprehend in one mental operation the entirety of what
has been asked so as to give any answer.” Ladd 427; see, e.g ., Editorials, The Hypothetical Question Again, 24 J.
Crim. L. & C. 517, 517–519 (1933). And juries surely found
following lengthy hypotheticals even more mystifying.

															For another, lawyers often used hypotheticals as
a preview of their closing arguments. See, e . g .,
Rosenberg 144 (“Assume . . . that he committed the act of
shooting the President under what he believed to be a Divine
command which he was not at liberty to disobey . . . so
that he could not resist the mental pressure upon him”); see also
S. Gross, Expert Evidence, 1991 Wis. L. Rev. 1113, 1162 (Gross);
Wigmore 2d §686, at 1095; Ladd 246. In doing so, they sometimes
sneaked in “irrelevant” information, Gross 1162, and excluded
necessary details, W. White, Insanity and the Criminal Law 86
(1923) (White) (describing the hypothetical question as
“eliminat[ing] from consideration every human element which every
common-sense man takes into consideration when he formulates an
opinion”). One medical expert declared that he “ha[d] never known a
hypothetical question, in a trial involving the mental condition of
the defendant, which in [his] opinion offered a fair presentation
of the case.” Ibid . As a result, experts either provided
answers that were entirely disconnected from “the actual case,” 1
Wigmore 2d §686, at 1095, or else they ignored the hypothetical
altogether, White 87.

															Because opposing counsel often disagreed for
strategic reasons about which facts should be included in a
hypothetical, constructing a hypothetical that the judge would
permit was often a tricky and contentious business. If counsel did
not include enough facts to satisfy opposing counsel, the
hypothetical would be met with an objection, and its sufficiency
would provide grist for an appeal. F. Rossi, Expert Witnesses 114
(1991). The threat of dragging out litigation led counsel to make
their hypotheticals even longer and more confusing. Ibid. By the early-20th century, this form of
testimony was scorned. In the second edition of his treatise,
issued in 1923, Wigmore proclaimed the hypothetical question “that
feature which does most to disgust men of science with the law of
Evidence.” 1 Wigmore 2d §686, at 1094. Around the same time, Judge
Learned Hand labeled hypotheticals “the most horific and grotesque
wen upon the fair face of justice.” Address of L. Hand: The
Deficiencies of Trials to Reach the Heart of the Matter, in
Lectures on Legal Topics, 1921–1922, p. 104 (1926). Professor
Charles T. McCormick described hypotheticals as “an obstruction to
the administration of justice.” Some Observations Upon the Opinion
Rule and Expert Testimony, 23 Texas L. Rev. 109, 128 (1945)
(McCormick). Experts shared these concerns; one lamented that
lawyers’ use of hypothetical questions was often “so unfair and
confusing and degrading that it does not clarify the issue nor help
achieve justice.” H. Hulbert, Psychiatric Testimony in Probate
Proceedings, 2 Law & Contemp. Prob. 448, 455 (1935).
Eventually, the use of hypothetical questions was “nearly
universally recognized as a practical disaster” by lawyers, judges,
and witnesses alike. Kaye §4.4, at 189.

															This state of affairs sparked efforts to
eliminate hypothetical questions as a requirement. See, e . g ., 1 Wigmore 2d §686, at 1094 (“The Hypothetical
Question must go, as a requirement. Its abuses have become so
obstructive and nauseous that no remedy short of extirpation will
suffice” (emphasis deleted)). Change began first in the courts,
which allowed experts to sit through trial and then provide their
opinion “ ‘upon the evidence.’ ” 3 C. Chamberlayne,
Modern Law of Evidence §§2482, 2483, pp. 3343–3346 (1912).

															More formalized rule changes soon followed. In
1937, the Commissioners on Uniform State Laws incorporated a
provision in their Model Expert Testimony Act that permitted
experts to give their opinions without preliminarily disclosing
their underlying facts or data. Advisory Committee’s Notes to Fed.
Rule Evid. 705. In quick succession, both the Model Code of
Evidence, issued by the American Law Institute in 1942, and the
Uniform Rules of Evidence, approved by the American Bar Association
in 1953, recommended abandonment of hypothetical questions. See
ALI, Model Code of Evidence Rule 409, Comment b , p. 211 (the
hypothetical question “has been so grossly abused as to be almost a
scandal”); Uniform Rules of Evidence, Rule 58, Comment, p. 194
(“This rule does away with the necessity of following the practice
(grossly abused) of using the hypothetical question”). In 1972, the
Federal Rules of Evidence followed suit with Rules 703 and 705, and
many States made similar changes.

															B

															What replaced hypotheticals was the procedure
exemplified by the Federal Rules of Evidence.[ 1 ] Rule 703 provides that an expert’s opinion may
be based on “facts or data in the case that the expert has been
made aware of or personally observed.” And “[u]nless the court
orders otherwise,” Rule 705 permits the expert to “state an
opinion—and give the reasons for it—without first testifying to the
underlying facts or data.”

															These facts or data need not be “admissible” in
evidence, and they are not admitted for the truth of what they
assert. Fed. Rule Evid. 703. Instead, these facts or data may , under some circumstances, be disclosed to the jury for
a limited purpose: to assist the jurors in judging the weight that
should be given to the expert’s opinion. Ibid. However, this
is not allowed unless the court determines that “their probative
value in helping the jury evaluate the [expert’s] opinion
substantially outweighs their prejudicial effect.” Ibid . And
to prevent the jury from improperly relying on basis testimony for
the truth of the matters it asserts, a judge must instruct
the jury upon request to consider such evidence only to assess the
quality of the expert’s testimony ( i . e ., to determine
whether an expert’s statements are reliable). See Advisory
Committee’s Notes on Fed. Rule Evid. 703, 28 U. S. C.
App., p. 393; Fed. Rule Evid. 105 (“If the court admits evidence
that is admissible . . . for a [limited] purpose—but not
. . . for another purpose—the court, on timely request,
must restrict the evidence to its proper scope and instruct the
jury accordingly”).

															This procedure is sensitive to the risk of
jurors’ mistakenly treating an expert’s basis testimony as evidence
of the truth of the facts of data upon which the expert relied. The
Rules provide important safeguards against this danger, such as the
stringent “probative value versus potential prejudice” test and the
requirement that a limiting instruction be given upon request.
Plus, of course, an expert’s lack of personal knowledge of the
“facts or data” that are called to his attention can be brought out
in cross examination and stressed in a closing argument.

															This modern system is more honest because it
reflects how experts actually form opinions. See Advisory
Committee’s Notes on Fed. Rule Evid. 703, at 393 (describing the
Rule as “designed to . . . bring the judicial practice in
line with the practice of the experts themselves when not in
court”). It is simpler and less likely to confuse. And it avoids
many of the pitfalls of the old procedure. It may not be
perfect—and evidence scholars have proposed a variety of
reforms—but it is unquestionably better than the old regime it
replaced.

															II

															In light of the woeful history of expert
testimony by hypotheticals, why has the Court disinterred that
procedural monstrosity? The Court reasons that “[i]f an expert for
the prosecution conveys an out-of-court statement in support of his
opinion, and the statement supports that opinion only if true, then
the statement has been offered for the truth of what it asserts.” Ante, at 14. Or put differently, “the truth of the basis
testimony is what makes it useful to the prosecutor; that is what
supplies the predicate for—and thus gives value to—the state
expert’s opinion.” Ibid. In other words, the Court seems to
think that all basis testimony is necessarily offered for
its truth.

															This is just plain wrong. What makes basis
evidence “useful” is the assistance it gives the fact-finder in
judging the weight that should be given to the expert’s opinion.
See Advisory Committee’s Notes on Rule 703 (basis testimony may be
brought before a jury to help it “evaluate the . . .
opinion”). And a trial judge must, upon request, instruct the jury
to consider it only for that purpose. If a judge rules that basis
evidence is not admitted for its truth and so instructs the
jury, where does the Court discern a Confrontation Clause
problem?

															The only possible explanation is that the Court
believes that juries are incapable of following such an
instruction, but that conclusion is inconsistent with commonplace
trial practice and with a whole string of our decisions. It is a
routine matter for trial judges to instruct juries that evidence is
admitted for only a limited purpose. This Court acknowledged as
much in United States v. Abel , 469 U.S.
45 (1984), when it noted that “there is no rule of evidence
which provides that testimony admissible for one purpose and
inadmissible for another purpose is thereby rendered inadmissible;
quite the contrary is the case.” Id ., at 56. In such
instances, courts use limiting instructions. See Fed. Rule Evid.
105; 1 R. Mosteller et al., McCormick on Evidence §59, pp.
481–483 (8th ed. 2020).

															And this Court has repeatedly upheld that
practice—even in “situations with potentially life-and-death stakes
for defendants” and even with respect to statements that are “some
of the most compelling evidence of guilt available to a jury,” Samia v. United States , 599 U.S. 635, 646–647 (2023).
These decisions “credi[t] jurors by refusing to assume that they
are either ‘too ignorant to comprehend, or were too unmindful of
their duty to respect, instructions’ of the court.” Id ., at
647. Indeed, we have described the assumption “ ‘that juries
will follow the instructions given them by the trial judge’ ”
as “ ‘crucial’ ” to “the system of trial by jury.” Marshall v. Lonberger , 459 U.S.
422 , 438, n. 6 (1983) (quoting Parker v. Randolph , 442 U.S.
62 , 73 (1979)); accord, Francis v. Franklin , 471 U.S.
307 , 324–325, n. 9 (1985).

															A brief survey of prior decisions shows how
firmly this Court has adhered to that practice. In Harris v. New York , 401 U.S.
222 (1971), the Court held that statements obtained from a
defendant in violation of Miranda v. Arizona , 384 U.S.
436 (1966), could be introduced to impeach that defendant’s
credibility, so long as the jury was instructed not to consider
them as evidence of his guilt. In Walder v. United
States , 347 U.S.
62 (1954), the Court affirmed the use of evidence obtained in
violation of the Fourth Amendment for impeachment when the trial
court had “carefully charged the jury” that it could not be
considered evidence of guilt. Id ., at 64. In Spencer v. Texas , 385 U.S.
554 (1967), the Court upheld the admission of evidence of the
defendant’s prior criminal convictions for the purpose of sentence
enhancement, provided that the jury was instructed that this
evidence could not be used in determining guilt. In Watkins v. Sowders , 449 U.S.
341 (1981), the Court presumed that a jury could properly
evaluate an eyewitness identification “under the instructions of
the trial judge.” Id ., at 347. And in Tennessee v. Street , 471 U.S.
409 (1985), the Court approved the admission of an accomplice’s
incriminating confession given the “pointe[d] instruct[ions] [of]
the trial court ‘not to consider the truthfulness of [the
confession] in any way whatsoever.’ ” Id ., at 414–415.

															Most recently in Samia , we held that a
limiting instruction was sufficient to defeat a Confrontation
Clause claim. In that homicide case, evidence showed that Samia had
traveled with his codefendant Stillwell to the Philippines to
commit a murder for hire. Samia , 599 U. S., at 640. The
trial court admitted Stillwell’s confession, which, as redacted,
stated that he was in a van with some “other person ” when
that person shot the victim, but the court told the jury that the
confession could be considered only for the purpose of determining
whether Stillwell himself was guilty. Id ., at 642. Samia
argued that admitting the confession even with the limiting
instruction would inevitably prejudice him because “other evidence
and statements at trial enabled the jury to immediately infer that
the ‘other person’ described in the confession was Samia himself.” Ibid . Nevertheless, we presumed that the jury was able
to follow the limiting instruction, and we therefore affirmed
Samia’s murder conviction.

															Our cases have recognized only one situation in
which a limiting instruction is insufficient: where a defendant is
directly incriminated by the extrajudicial statements of a
non-testifying codefendant. Bruton v. United States , 391 U.S.
123 (1968). We have declined to extend that exception, see Samia , 599 U. S., at 654, and the evidence in question
in Bruton cases is worlds away from an expert’s basis
testimony. If the Court thinks otherwise, it needs to explain why
basis testimony falls into the Bruton category and creates a
greater risk of juror confusion than all the other situations in
which the Court has assumed that jurors are capable of following
limiting instructions.

															III

															The Court’s assault on modern evidence law is
not only wrongheaded; it is totally unnecessary. Today’s decision
vacates the Arizona court’s judgment because the testifying
expert’s testimony was hearsay. I agree with that bottom line, but
not because of the majority’s novel theory that basis testimony is
always hearsay. Rather, I would vacate and remand because the
expert’s testimony is hearsay under any mainstream conception,
including that of the Federal Rules of Evidence.

															To understand why, begin with the facts. A state
forensic scientist, Elizabeth Rast, tested items seized from the
defendant and concluded that they were marijuana and
methamphetamine. Rast took notes of her tests, see App. to Pet. for
Cert. 88a–126a, and she signed a report confirming the results, see id ., at 85a–87a. At trial, Rast was unavailable, so the
prosecution called another forensic scientist, Greggory Longoni, to
provide his expert opinion about the testing, and Longoni relied on
Rast’s report in doing so.

															Under Rules 703 and 705, Longoni could have
offered his expert opinion that, based on the information in Rast’s
report and notes, the items she tested contained marijuana or
methamphetamine. In so answering, he would acknowledge that he
relied on Rast’s report and lab notes to reach his opinion. He
could have also disclosed the information in the report, if the
court found that the probative value of that information
substantially outweighed the risk of prejudice. See Fed. Rule Evid.
703. But he could not testify that any of the information in the
report was correct—for instance, that Rast actually performed the
tests she recorded or that she did so correctly. Nor could he
testify that the items she tested were the ones seized from Smith.
Longoni did not have personal knowledge of any of these facts, and
it is unclear what “reliable” scientific “methods” could lead him
to intuit their truth from Rast’s records. Fed. Rule Evid. 702(c)
(defining a permissible expert opinion).

															The strictures of the Federal Rules here track
the requirements of our Confrontation Clause precedents. If Longoni
testified to the truth of the fact that Rast actually performed the
tests indicated in her report and notes and that she carried out
those tests properly, he violated the Confrontation
Clause—assuming, of course, that the notes were “testimonial,” a
question that the Court does not reach. But he would also violate
the Federal Rules, which do not allow experts to testify to the
truth of inadmissible hearsay. In other words, except for the
question whether Rast’s report was “testimonial,” the Federal Rules
and the requirements of the Confrontation Clause are the same. This
case thus offers no occasion to blow up the Federal Rules.

															As it happens, I agree with the Court that
Longoni stepped over the line and at times testified to the truth
of the matter asserted. The prosecution asked Longoni on several
occasions to describe the tests that Rast performed or to swear to
their accuracy, and Longoni played along. He stated as fact that
Rast followed the lab’s “typical intake process” and that she
complied with the “policies and practices” of the lab. App. to Pet.
for Cert. 40a–42a. He also testified that Rast used certain
“scientific method[s]” to analyze the samples, such as performing
certain tests or running a “blank.” Id ., at 41a–42a,
46a–48a. By asserting these facts as true, Longoni effectively
entered inadmissible hearsay into the record, thus implicating the
Confrontation Clause. The Court could have said that—and stopped
there.

															*  *  *

															For more than a half-century, the Federal Rules
of Evidence and similar state rules have reasonably allowed experts
to disclose the information underlying their opinion. Because the
Court places this form of testimony in constitutional doubt in many
cases, I concur only in the judgment. Notes 1 I refer to the Federal
Rules to illustrate the consequences of the Court’s opinion. The
witness in this case testified in an Arizona state court, and his
testimony was therefore governed by the relevant state rules, which
are virtually identical to the Federal Rules. Of course, the
Arizona courts are free to interpret those rules as they see fit,
and I do not address the question whether the witness’s testimony
was proper under Arizona law.

Summary: The Supreme Court ruled that an expert witness cannot simply repeat another analyst's statements as fact to support their opinion without violating the Confrontation Clause, which guarantees a defendant the right to confront witnesses against them. If the analyst is absent, their statements are considered hearsay and are generally inadmissible unless they fall under a specific exception. This ruling emphasizes the importance of an expert's firsthand knowledge and their ability to be cross-examined.