PTAB Left to Mitigate the Damage from Collateral Estoppel

Collateral estoppel, or issue preclusion, is the legal doctrine that bars a litigant from re-litigating in subsequent litigations an issue that it lost in an earlier litigation. The doctrine had been applied in the administrative context previously, and in Maxlinear, Inc. v. CF Crespe, the Federal Circuit confirmed that it applies in IPR proceedings. In doing so, however, the court left the Board to resolve an interesting practical question as to how exactly collateral estoppel should apply on remand. Depending on how the Board resolves this practical issue, Maxlinear may provide petitioners a significant windfall as they will be able to challenge claims on the basis of prior art that they never cited to the Board. 

The Maxlinear decision involved an appeal from a final written decision holding that certain claims of U.S. Patent No. 7,075,585 were not proven unpatentable. The decision confirming patentability was the third final written decision the Board entered concerning this patent. In two prior final written decisions, the Board held that claims of the patent—including independent claims 1 and 17—were unpatentable in view of prior art not raised in the third IPR trial. The two prior decisions were appealed and the Federal Circuit affirmed those decisions while the appeal of the third decision was pending before the court.

In the appeal of the third decision, collateral estoppel became an issue. In that decision, the Board had found claims 1 and 17 patentable in view of the art raised in that proceeding, but now the Federal Circuit had finally adjudicated those claims unpatentable. The court held that collateral estoppel necessitated reversal of the Board’s finding of patentability in the third decision because that finding rested entirely on the patentability of independent claims 1 and 17, a finding that collateral estoppel now barred.

The court reversed not only the Board’s finding that independent claims 1 and 17 were not proven unpatentable but also its finding that certain dependent claims not addressed in the prior two decisions were not proven unpatentable. According to the Federal Circuit, because the Board’s decision finding the dependent claims were not proven unpatentable rested entirely on its finding that the independent claims were not unpatentable, the Board’s findings with respect to the dependent claims must also be reversed and remanded for further consideration. 

Remand is where things get interesting. At first blush, it would seem that the Board would only need to repeat its prior analysis on remand and explicitly apply that analysis to the dependent claims—after all, if the independent claims were patentable, then the dependent claims would be too. But the Federal Circuit ordered the Board to consider whether the dependent claims were patentable in view of the prior art raised in the first two IPR trials—art that was never before the Board in the third IPR trial. 

On its face, the Federal Circuit opinion appears to require that the patent owner defend the patentability of its claims not only against the prior art that was actually at issue in the IPR trial but also prior art that was not raised in that trial. Whether the Board will provide the patent owner with the opportunity to submit new briefing or expert declarations concerning the “new” art is an issue that the Board will need to wrestle with on remand. 


Patent owners should check back in a few months from now to see how the Board handles this case. In any event, the decision highlights the risks multiple petitions present to patent owners and the advantage that such a tactic can provide to petitioners.