Patent owner can’t sue alleged infringer again on reexamined claims
The following case illustrates a tension between the claim preclusion doctrine which bars relitigation of claims decided in earlier litigation between the parties (i.e., res judicata) and the reexamination procedure at the United States Patent and Trademark Office. Claim preclusion provides that the parties to a legal proceeding are bound to the final judgment of the federal or state court with respect to every matter that was presented or could reasonably have been presented as long as it arose out of the same facts. The reexamination procedure is an administrative procedure at the Patent Office that provides for the reexamination of the patent claims based on prior art documents. During reexamination, the patent claims may be amended to avoid prior art references – as long as they are not broadened. As such, the claims of the reexamined patent may be different compared to the claims in the original patent. The tension arises from whether the patent owner can sue the alleged infringer in a second lawsuit based on the reexamined patent claims when the original patent claims have been adjudicated in a first lawsuit.
In Senju Pharmaceutical v. Apotex (Fed. Cir. 2014), Senju (patent owner) sued Apotex (alleged infringer) for patent infringement in a first lawsuit. During litigation, certain patent claims were held to be invalid for being obvious in light of newly uncovered prior art. The patent owner then had its patent reexamined in light of the newly uncovered prior art. The patent emerged from the reexamination procedure with narrowed claims. The patent owner filed a second lawsuit against the alleged infringer based on the reexamined patent claims.
In order to determine whether claim preclusion applies, one element that the courts consider is whether the second lawsuit is based on the same cause of action. One factor in determining whether the first and second lawsuits involve the same cause of action is whether the same patents are involved in both lawsuits. In answer to this question, the Federal Circuit notes that a reexamined patent is the same patent as the original patent. The reexamined patent maintains the same patent number and patent application serial number. Moreover, patent statutes prohibit the introduction of new matter and enlargement of the claim’s scope. Accordingly, any action based on the reexamined patent claims is based on the same cause of action as the original patent claims. Hence, the court concluded that claim preclusion applied.
Here, both parties cited to the Aspex Eyewear case which generally found that claim preclusion barred a second lawsuit based on reexamined claims. In Aspex Eyewear the court indicated that the original patent claims and the reexamined patent claims were not materially different. Hence, the reexamined patent claims involved the same cause of action as the original patent claims. The differences in the reexamined claims were merely included to avoid the prior art and maintain validity of the patent.
Senju (the patent owner) latched onto the “materially different” language and contended that a detailed analysis of the original and reexamined claims is required to determine whether a new cause of action exists. Based on the facts of this case, the Federal Circuit disagreed that a new cause of action existed but left open the possibility that upon a clear showing that the reexamined patent claims are materially different from the original patent claims, then claim preclusion may not apply to reexamined patent claims. However, the Federal Circuit did not provide any examples that might apply. Thus, it is possible that claims which a court finds are invalid may be relitigated by the same parties if the Patent Office’s reexamination of those claims in light of the prior art that invalidated them results in narrower claims that are materially different with a clear showing than those involved in the first.
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