The only legitimate question, he says, is whether the claimed subject matter is "new, useful, and unobvious." Judge Rich could not agree that the implementation of a natural principle must be "inventive" rather than concededly conventional (as Flook had conceded). To him, that improperly mixed obviousness under section 103 up with statutory subject matter under section 101. But Judge Rich overlooked what Justice Stevens pointed out--that Flook did not "purport" to have implemented the process in anything but a conventional way and did not purport to have added anything to what was previously known but the use of the smoothing formula. Justice Stevens saw the case as one in which Flook did not even purport to have invented anything capable of being patented. (Justice Stevens responded to the "Bergy" critique in his dissenting opinion in the "Diehr" case.) Actually, the concession by Flook made the "Flook" case an easy one. But one could hardly expect any applicant in a subsequent case to make a similar concession. It is unclear how to apply the principle of the "Flook" case to other cases where no such concession exists. In one class of case, where the implementation is utterly trivial on its face, as in "Funk v. Kalo Inoculant Co.", the applicability of the same principle seems clear. But that appears to be the outer limit of the easy case. Once reasonable persons can differ on whether the implementation is barely removed from the natural principle, it would seem that the "Flook" principle cannot be employed. If a full-scale "Graham v. Deere" analysis must be used to evaluate the implementation, it would seem that the case can no longer be disposed of on section 101 grounds. That is what appears to have happened in the next member of the trilogy, "Diamond v. Diehr". For many years commentators thought that "Diehr" overruled "Flook" or reduced it to innocuous desuetude. In "Mayo v. Prometheus", however, the Supreme Court "rehabilitated" "Flook" and harmonized it, "Diehr", and the other decisions of the Supreme Court as well as the 19th century English decision of "Neilson v. Harford". The "Mayo" Court read the prior cases to establish as a centerpiece of this branch of law that for a claimed invention based on the implementation of a law of nature or a "principle" to gain a patent monopoly, the implementation must not be conventional or trivial but must instead be inventive, which is to say, presumably, novel and not obvious.