machine-or-transformation test is not the exclusive test of patentability. At the same time, the Court (per Justice Kennedy) held, 5-4, that Bilski's software, business-method patent application was patent ineligible because it was directed to an abstract idea, largely preempting hedging as a business expedient. But the majority declined to rule all business-method patents ineligible. Justice Stevens, in one of his last opinions before retiring from the Court, concurred in the judgment but disagreed with the majority's rationale. Joined by Justices Ginsburg, Breyer, and Sotomayor, he argued that the claimed invention was patent ineligible because it was a business method (advancing much the same analysis as that in Judge Dyk's opinion in the Federal Circuit) and therefore outside the reach of the patent system. Justice Breyer filed a concurring opinion in which he explained the points on which all nine justices agreed. Mayo case Bilski was followed by the Court's unanimous opinion in Mayo Collaborative Services v. Prometheus Labs, Inc. Although it did not involve a software patent (it concerned a medical assay implementing a natural principle), it stated a methodology for determining patent eligibility that is currently dominant in software cases. It revived the approach of the Flook and Neilson cases, which is to treat the underlying principle, idea, or algorithm on which the claimed patent is based as if it were part of the prior art and to make patent eligibility turn on whether the implementation of it is inventive. Alice case In May, 2013, the CAFC issued a fragmented en banc decision in CLS Bank International v. Alice Corp. in which the judges were unable to reach a coherent unified decision on the patentability of the business-method software claims at issue. The case went to the Supreme Court, which decided it on June 19, 2014. The Court used the analysis from the Mayo decision and held Alice's patents invalid as directed to an abstract idea. As in Bilski, the Court did not rule all business-method patents ineligible. However, the Court's requirement (as in Mayo and Flook) for an "inventive concept" for the implementation of the principle underlying the claimed method and its insistence that "merely saying [to] apply it with a computer" is not enough to confer patent eligibility may doom many or most business-method software patents. Post-Alice period Since the Alice decision, the Federal Circuit and district courts have held a number of business-method patents to be