Inter Partes reviews (IPRs) and post grant reviews (PGRs) are procedures for challenging the validity of patents at the U.S. Patent and Trademark Office (PTO). IPRs and PGRs went into effect as a result of the America Invents Act (AIA) on September 15, 2012, and were intended to replace inter partes reexamination.

In the nine years since their inception, hundreds of PGRs and thousands of IPRs have been filed. When the procedures were initiated, institution and invalidation rates were high, leading Chief Judge Rader to call the PTAB “death squads” for patents. Much has changed since then with institution rates falling, claim construction standards changing (from the broadest reasonable interpretation to the Phillips v. AWH Corp. standard used in federal courts), an increase in allowance of motions to amend, and an increase in discretionary denials based on parallel litigations.