On December 21, 2020, the USPTO published its final rule allocating the burdens of persuasion for motions to amend and the patentability of proposed substitute claims in IPR, PGR, and CBM proceedings. This rule package follows up on the USPTO’s notice of proposed rulemaking released in October 2019. This rule largely codifies the existing practice and the Federal Circuit’s precedent in Aqua Products and other decisions regarding motions to amend in AIA trials.