In this episode of the Post-Grant Podcast, Andy Zappia, Nick Gallo, and Bryan Smith explore the evolving landscape of estoppel in inter partes review (IPR) and post-grant review (PGR) proceedings at the Patent Trial and Appeal Board (PTAB). The discussion centers around the recent Federal Circuit decision in the Ingenico case, which narrows the scope of IPR estoppel, and its potential tension with the PTAB's current approach to discretionary denial. The team delves into the implications of this decision for patent challengers, particularly in light of new PTAB guidance and recent cases that highlight the complexities of navigating estoppel and discretionary denial.