In a claim construction hearing in Panduit Corp. v. Corning Inc., No. 5:18-cv-00229 (E.D.N.C. July 2, 2021), the court denied plaintiff's request that the defendant be judicially estopped from arguing for a claim construction that differed from the one offered during a related inter partes review.  

The defendant had previously asserted a claim construction before the Patent Trial and Appeal Board, and then argued for a different claim construction before the district court. In response, the plaintiff sought to judicially estop the defendant from asserting this differing construction before the district court, claiming that the two positions were factually incompatible. The court denied the plaintiff's motion for judicial estoppel.

The court considered three non-exhaustive elements to determine whether application of judicial estoppel was appropriate:

  • The party to be estopped must be asserting a position that is factually incompatible with a position taken in a prior judicial or administrative proceeding;
  • The prior inconsistent position must have been accepted by the tribunal; and
  • The party to be estopped must have taken inconsistent positions intentionally for the purpose of gaining unfair advantage.

The parties did not dispute whether the first two elements had been met—the defendant's claim construction offered to the court was factually incompatible with the construction it offered to the PTAB, and the PTAB had accepted the defendant's proposed claim construction.  

But the court found that plaintiff had not sufficiently shown the third element.  Specifically, the court found the plaintiff had failed to show the defendant "engaged in malfeasance, purposefully inequitable conduct, or otherwise intentionally misled" the court or the PTAB when presenting its claim construction positions.  The court thus held the defendant was not judicially estopped from arguing for a different claim construction than the one offered during the related inter partes review.

In its opinion, the court emphasized that judicial estoppel is a severe sanction that prevents a party from asserting a position that would normally be available to them.  Judicial estoppel is thus reserved for parties who have sought an unfair advantage.  Where a party asserts differing claim constructions before differing tribunals, that alone will not necessarily suffice to invoke judicial estoppel. 

* Samantha Leff is a Summer Associate at Finnegan.

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