Inconsistency Across Related Cases is Precluded
When challenging related patents at the Patent Trial & Appeal Board (PTAB), it is not uncommon to present similar grounds of unpatentability across related filings— for example, where the claim sets are substantially similar. In such scenarios, it is expected that the PTAB will arrive at consistent determinations across the filings. Of course, there is no guarantee, that the same judge will decide all of the cases. In such instances, there is a possibility of inconsistent results, especially where the challenges are advanced at different times.
For example, party A might challenge a parent patent in an IPR, and lose on a question of obvious under 103. When a continuation patent issues a bit later, Party A may attempt to challenge the continuation on the same grounds (perhaps bolstered by a better presentation or additional evidence). In such a scenario, is the Board free to change its mind? Or is the Board collaterally estopped given the earlier determination, and the same party pursuing the same argument?