While post-grant review provides a petitioner a forum to challenge a patent on any basis of patentability, IPRs are limited to challenges on the grounds of novelty and nonobviousness based only on patents and printed publications. A challenged patent in an IPR is not presumed valid, unlike in district court patent trial litigation (where there is litigation patent judgements). IPRs are trial-like proceedings conducted in front of a panel of administrative patent judges—the Patent Trial and Appeal Board (PTAB). In a patent trial, parties may collect evidence by deposing experts and inventors, and the parties support their cases with oral arguments before the PTAB.








