The US Court of Appeals for the Federal Circuit reversed a district court order excluding expert validity testimony based on collateral estoppel stemming from an inter partes review (IPR) proceeding of a related patent, finding that an unpatentability decision in an IPR does not collaterally estop a patentee from making validity arguments about related claims in a district court litigation. ParkerVision, Inc. v. Qualcomm Inc., Case Nos. 22-1755; 24-2221 (Fed. Cir. Sept. 6, 2024) (Lourie, Mayer, Stark, JJ.)

This case has a long and complicated history. In 2011, ParkerVision sued Qualcomm for alleged infringement of eight patents related to wireless communications technology. In October 2013, a jury returned verdicts rejecting Qualcomm’s invalidity defense, finding 11 claims across four patents to be infringed by Qualcomm, and awarded $172 million in damages to ParkerVision.

In June 2014, the district court granted Qualcomm’s motion for a judgment as a matter of law on noninfringement, which the Federal Circuit affirmed in late 2015. Meanwhile, ParkerVision filed a second case against Qualcomm in May 2014 alleging infringement of 11 more patents. That case was stayed in favor of a Section 337 investigation that ParkerVision filed against Qualcomm at the International Trade Commission.

Qualcomm then filed 10 petitions for IPR, six of which targeted one of ParkerVision’s patents. While the challenged apparatus claims of that patent were found unpatentable during the IPR, the challenged method claims survived. The district court statutory stay (during the Commission proceeding) was lifted in December 2018. Prior to trial, the district court granted Qualcomm’s Daubert motions seeking to exclude ParkerVision’s expert’s testimony on invalidity due to collateral estoppel arising from the IPRs, and the expert’s testimony on infringement for being unreliable. The district court granted Qualcomm’s motion for summary judgment of noninfringement based on its finding that the asserted claims were materially similar to the claims from the first case. ParkerVision appealed.

In July 2024, after the briefing was completed and the Federal Circuit held oral argument, the Court dismissed the appeal for lack of appellate jurisdiction and returned it to the district court because Qualcomm’s invalidity counterclaims had not been adjudicated. The parties then filed a joint motion at the district court seeking entry of a final judgment, which was granted in August 2024. ParkerVision appealed again.

The Federal Circuit reinstated ParkerVision’s initial appeal and reversed the district court’s determination. On the summary judgment of noninfringement, the Court rejected the collateral estoppel finding because the district court failed to conduct claim construction to determine whether the scope of the claims was the same as in the first case. As for the district court’s exclusion of expert validity testimony due to the IPRs, the Federal Circuit concluded that because of the different legal standards for proving invalidity (preponderance versus clear and convincing), a finding underlying an unpatentability decision in an IPR does not collaterally estop a patentee from making validity arguments regarding related claims in district court litigation.

Finally, the Federal Circuit concluded that the district court had abused its discretion in excluding ParkerVision’s expert’s infringement testimony because of the expert’s lack of testing and simulations. The Court pointed to testimony from Qualcomm witnesses that relying on testing by others was sufficient and simulation of circuits depicted in schematics of record was not required.

The Federal Circuit therefore remanded the case back to the district court.