PGR permits raising the most grounds for challenging validity, but such petitions may only be filed within nine months after an AIA (first-to-file) patent is issued, based on applications filed on or after March 16, 2013. After this time period has passed or completion of a PGR trial, an IPR petition may be filed.
A petitioner may request a PGR to challenge patentability based on virtually any ground that could be raised in federal court: anticipation or obviousness based on printed publications, public use, on-sale activity, other public disclosures; or lack of compliance with the statute’s written description, enablement, definiteness, or eligibility requirements. For the PTAB to grant a PGR petition, the petition must show that it is “more likely than not that at least one claim is unpatentable” or the petition must raise “a novel or unsettled legal question that is important to other patents or applications.”
Following the PTAB’s final written decision on the instituted PGR, estoppel provisions prevent the petitioner from raising in another proceeding, grounds that were actually raised in a PGR.