Post-Grant Review Proceeding Filings Ramp Up In addition to inter partes review (IPR) and covered business method (CBM) review proceedings, the America Invents Act (AIA) provides for post-grant review (PGR) proceedings. PGR allows a broader array of challenges to be brought against a patent, including challenges to patent eligibility, enablement, and written description, as well as anticipation and obviousness challenges using printed publications, public uses, or sales. However, Section 6(f) of the AIA restricts PGR to patents that are subject to the first-to-file provisions of the AIA. Under Section 3(n)(1) of the AIA, the first-to-file provisions “shall apply to any application for patent, and to any patent issuing thereon, that contains or contained at any time a claim to a claimed invention that has an effective filing date . . . that is on or after” March 16, 2013. Even then, PGR is available during a limited window that lasts only nine months after the patent issues.