In Oil-Dri Corp. of Am. v. Nestle Purina Petcare Co., the district court granted a renewed estoppel motion under the rationale that references relied upon to challenge the validity of an asserted patent reasonably could have been presented in a previous IPR challenging the asserted patent. Under 35 U.S.C. §§315(e)(2) and 325(e)(2), a petitioner is estopped from challenging the claims of a patent-in-suit on any ground of challenge that the petitioner “raised or reasonably could have raised during” the IPR or PGR. As discussed in our previous article, in Shaw Industries Group, Inc. v. Automated Creel Systems, Inc., the Federal Circuit held that estoppel did not apply to grounds of challenge presented in an IPR petition but denied institution by the PTAB. In Shaw, the issue of what constitutes prior art references that a petitioner “reasonably could have raised” was not before the court. Since Shaw, district courts have examined the reach of estoppel under §§315(e) and 325(e) by grappling with what constitutes prior art that “reasonably could have [been] raised” in a post-grant proceeding at the PTAB.

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