The case is Minerva Surgical, Inc. v. Hologic, Inc., majority opinion by Justice Kagan, with a dissent by Justice Alito and another by Justice Barrett (joined by Justices Thomas and Gorusch). From the majority opinion:
In Westinghouse Elec. & Mfg. Co. v. Formica Insulation Co., 266 U. S. 342, 349 (1924), this Court approved the “well settled” patent-law doctrine of “assignor estoppel.” That doctrine, rooted in an idea of fair dealing, limits an inventor’s ability to assign a patent to another for value and later contend in litigation that the patent is invalid. The question presented here is whether to discard this century-old form of estoppel. Continuing to see value in the doctrine, we decline to do so. But in upholding assignor estoppel, we clarify that it reaches only so far as the equitable principle long understood to lie at its core. The doctrine applies when, but only when, the assignor’s claim of invalidity contradicts explicit or implicit representations he made in assigning the patent (p.1).
As for the dissents Justice Alito would dismiss the writ of certiorari as having been improvidently granted, because in his view the Court cannot "decide the question that the petition in this case presents unless we decide whether Westinghouseshould be overruled," and neither the majority nor the principal dissent address that issue (Alito dissent p.5). As for the principal dissent, it argues that the 1952 Act abrogated assignor estoppel because the Act doesn't mention the doctrine, and the doctrine was not "part of the well-settled common-law backdrop against which Congress legislated in 1952" (Barrett dissent, p.1). To be honest, I didn't follow this case as closely as many of my colleagues as it was making its way up to the Court; but for what it's worth, the majority opinion seems sensible to me, and both dissents a bit silly in their adherence to a hyper-textualist approach to patent law that has little if any relationship to the Court's traditional practice, reaching back to the nineteenth century, of resolving questions of patent law.