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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