Federal Circuit Revisits Assignor Estoppel

Published date19 August 2022
Subject MatterIntellectual Property, Litigation, Mediation & Arbitration, Patent, Trials & Appeals & Compensation
Law FirmOblon, McClelland, Maier & Neustadt, L.L.P
AuthorMr Richard D. Kelly

On August 11, 2022, the Federal Circuit issued its opinion in the remand of Hologic, Inc. v Minerva Surgical, Inc. from the Supreme Court's decision limiting the application of assignor estoppel to where the assignor is taking in litigation a position inconsistent with his prior representations in assigning the patent. In this case the issue was whether the issued claims are materially broader than the claims in the assigned application, Minerva Surgical, Inc. v. Hologic, Inc., 141 S. Ct. 2298, 2302, 2309 (2021). The Supreme Court in Minerva refused to discard the concept of assignor estoppel but instead held that the concept comes with limits and "reaches only as far as the equitable principle long understood to lie at its core." The Supreme Court held that assignor estoppel "applies only when an inventor says one thing (explicitly or implicitly) in assigning a patent and the opposite in litigating against the patent's owner." Id. at 2304. Stated differently, where the assignor has not any explicit or implicit representations which conflict with an invalidity defense.

In this case Minerva asserted that the challenged claim in the assigned patent was materially broader than the ones assigned the original application and thus representations as to the claims existing at the time of the assignment were not relevant to the issued claim. The Supreme Court did not reach this issue because the Federal Circuit had held that it was irrelevant since assignor estoppel applied in either event whether the claim was broader or narrower claim than those assigned. The issue turned on whether claim 1 of the patent-in-suit, U.S.P. 9,095,348 ('348) was materially broader in scope than the invention described in its parent application 09/103,072, which matured into U.S.P. 6,813,520 after the assignment from NovaCept, the original assignee of the '072 application, to Cytec. The '072 application claimed the invention of Mr. Truckai who assigned the application to NovaCept. Mr. Truckai was a founder of NovaCept. NovaCept was acquired by Cytec in 2004 for $325 million in 2004. In the agreement assigning the '072 application to Cytec, NovaCept warranted that it had "no present knowledge from which it could reasonably conclude" that the assigned intellectual property rights were invalid or unenforceable. The NovaCept-Cytec agreement assigning its rights to the '072 application included the rights to its patents and any continuation, continuation-in- part, or divisional patent...

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