When the inter partes review procedure first came into force, many would-be petitioners were wary of its seemingly broad estoppel provision. Petitioners were concerned about the risk of losing a patent validity challenge in an IPR, and being estopped from challenging the same patent claims in district court. But as some recent decisions from the Federal Circuit, a few district courts and the Patent Trial and Appeal Board have shown, it is not all doom and gloom for a petitioner who fails to invalidate some or all challenged claims in an IPR. These recent decisions have provided much-needed clarity on certain aspects of the estoppel provision, and have alleviated some of the concerns of IPR petitioners by limiting the reach of estoppel in successive IPRs and in district court validity challenges. In this article, Finnegan attorneys  Barbara C. McCurdy and  Arpita Bhattacharyya discuss these decisions.

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