Post Grant Review (“PGR”) is a Patent Trial and Appeal Board (“PTAB”) proceeding established under 35 U.S.C. § 321 that permits the PTAB to review the patentability of claims in a patent based on any grounds under 35 U.S.C. § 282(b)(2) or (3). PGR proceedings only apply to patents filed post-American Invents Act (“AIA”) (i.e., with a priority date after March 16, 2013) and must be filed by a third party within nine months of a patent being granted or reissued. 35 U.S.C. § 321. For this reason, PGR practice is still in its infancy, as many post-AIA patents are just now starting to issue.