PGRs Still Rare – Is Estoppel The Reason?, PTAB Litigation Blog

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A Post-Grant Review can be used to challenge newly-issued patents on wide-ranging grounds, but PGRs remain relatively unpopular: statutory estoppel may be a reason why.

The America Invents Act ("AIA") created new procedures for challenging the validity of patents at the PTAB.  One of those procedures is Post-Grant Review ("PGR"). PGR is available for any issued patent claiming priority after March 16, 2013. The window for a PGR petition is time-limited: a PGR challenge must be filed in the first nine months after a patent issues, but the petitioner can raise any grounds for invalidity that can be asserted in district court—including subject matter ineligibility under § 101, invalidity based on product prior art under §§ 102 or 103, and invalidity based on written description or enablement under § 112. This is unlike Inter Partes Review (“IPR”), which is strictly limited to §§ 102 and 103 patentability challenges based on prior art patents or printed publications.

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