‘Collateral estoppel’ means that when a judge, jury or other tribunal finally decides an issue in litigation between two parties, then the decision controls the same issue between the same parties in subsequent litigation. The losing party can appeal a decision (usually), but once the appeals from the decision are exhausted the issue is decided now and forever. The reason is simple – it would be incredibly costly to the courts, the parties and to society as a whole to re-litigate the same issue between the same parties over and over again. In common parlance, the parties get ‘one bite of the apple,’ and no more. Which brings us to patents, and how a patent owner set a trap for himself and promptly fell in.

First a little background.  When a patent owner sues an infringer for patent infringement, the usual strategy for the infringer is to petition the USPTO for ‘interpartes review’ (IPR).  IPR is a review of the validity of the patent(s) by the USPTO based on prior art cited by the infringer.  If the infringer wins the IPR, then all or part of the patent is declared unenforceable (by the USPTO), and all or part of the lawsuit in Federal court will be dismissed (by the Federal judge).  If the patent owner wins the IPR, then the infringer cannot challenge the patent in Federal court on the same grounds or on other grounds that the infringer could have raised in the IPR.  Either way, both parties save time and money on litigating the validity of the patent in Federal court.  That’s the theory, anyway.

What about the situation where the patent owner has a family of patents and accuses the infringer of infringing multiple patents in the family.  Does an IPR decision relating to one patent family member bind the same parties for a different patent family member? 

In short, the answer is yes.  If the issues are the same, a final decision relating to one patent family member will collaterally estop another patent family member.

The Federal Circuit Court considered this question in Google v Hammond, decided December 8, 2022.  Hammond sued Google for infringing three related patents.  Google petitioned for IPR for all three patents.  The resulting IPR killed two of the three patents, but some of the claims of the third patent survived the IPR.  Google appealed the USPTO decisions for the third patent.  Hammond did not appeal the loss of the first and second patents.  Because Hammond did not appeal the two patents, all appeals were exhausted for those two patents, and the IPR decisions for those two patents were final and set in stone.  

The Federal Circuit Court held that a claim finally decided to be invalid in the first two (un-appealed) IPRs collaterally estopped a similar claim that was held to be valid in the IPR but that was on appeal and not final.  The claim, held valid under the IPR, was just as dead as the final claims determined to be invalid under the IPR.

The bottom line? When pursuing patent infringement for multiple patents or multiple claims, (a) make sure that you understand collateral estoppel and (b) appeal everything.  Otherwise, you may set a trap for yourself, fall into your own trap, and lose your patent rights.

— Robert Yarbrough, Esq.