The 2011 passage of the America Invents Act (AIA) resulted in a seismic shift in patent litigation and disputes in the United States. The AIA brought with it new post-grant proceedings, including inter partes review (IPR) and post-grant review (PGR), that could be used to challenge the validity of patents in a quasi-litigation proceeding before the U.S. Patent and Trademark Office's (USPTO's) Patent Trials and Appeals Board (PTAB). Since their inception, over 15,000 such proceedings have been filed, making them an integral part of the process for resolving patent disputes in the United States.