When considering the prospects of a post-grant trial before the Patent Trial and Appeal Board (PTAB) at the U.S. Patent and Trademark Office (USPTO), one often realizes that some of the strongest prior art that could form a basis for the patent challenge has already been considered by the USPTO. For example, the strongest prior art may have been applied by an examiner in a rejection (which the patent owner overcame) during the ex parte prosecution of the application that led to the patent or during an ex parte reexamination. If the PTAB is willing to institute a post-grant trial notwithstanding the USPTO’s previous consideration of the prior art, the petitioner stands a good change of ultimately prevailing, as studies have shown that patent challengers have high success rates once the PTAB grants a petition to institute a post-grant trial. Thus, often the biggest question for a would-be petitioner is whether the PTAB will institute a post-grant trial on based on the previously considered prior art.