Findings of Invalidity in IPR Proceeding Cannot Form the Basis of Collateral Estoppel in District Court Litigation

In ParkerVision, Inc. v. Qualcomm Inc., Nos. 2022-1755, 2024-2221 (Fed. Cir. Sept. 6, 2024), the Federal Circuit reversed a district court’s order excluding testimony of ParkerVision’s expert because the district court erred in finding that the expert’s testimony was inconsistent with the PTAB’s invalidity findings in a related IPR proceeding. The Federal Circuit also vacated the district court’s summary judgment of non-infringement based on collateral estoppel and the district court’s exclusion of ParkerVision’s expert’s testimony as unreliable. 

This ruling is the latest in a long history of disputes between the parties. In 2011, ParkerVision sued Qualcomm for infringement of four patents relating down-conversion and up-conversion in wireless communications systems. A jury returned a verdict finding Qualcomm infringed multiple claims across the four patents. The district court, however, entered judgment of noninfringement as a matter of law and the Federal Circuit affirmed that judgment.

In a 2014 follow-on litigation, ParkerVision alleged that Qualcomm's products infringed various additional patents not at issue in the 2011 action. Qualcomm then filed several petitions for inter partes review challenging one of the patents ParkerVision asserted in the 2014 action. The PTAB determined the challenged apparatus claims of this patent were not patentable, while the challenged method claims were. The Federal Circuit affirmed the PTAB’s unpatentability determination of the apparatus claims.

As trial approached in the 2014 action, the district court granted motions by Qualcomm to exclude ParkerVision’s expert testimony on invalidity as contradicting the PTAB’s findings and to exclude his testimony on infringement as being unreliable. The district court also granted Qualcomm’s motion for summary judgment that the 2011 action collaterally estopped ParkerVision from asserting infringement in this case. The district court also found that the PTAB’s determination of unpatentability collaterally estopped ParkerVision from asserting related claims from the same patent.  ParkerVision appealed.

The Federal Circuit found that the district court erred by applying collateral estoppel without performing the proper claim construction analysis. Instead of examining the intrinsic evidence, the district court improperly relied entirely on extrinsic evidence to determine that the claims at issue were essentially the same as those previously litigated in the 2011 action. Summary judgment premised on collateral estoppel was thus inappropriate.

The Federal Circuit also found that due to different evidentiary standards in PTAB and district court proceedings, a finding underlying an unpatentability decision in an IPR proceeding does not estop a patentee from making validity arguments regarding separate, related claims in a district court litigation. While an affirmance of the Board’s invalidity findings may create estoppel, the method claims at issue were found patentable and thus remain presumptively valid. The Federal Circuit also reversed the district court’s exclusion of the expert’s testimony as being unreliable, determining that an expert is not required to conduct testing on an accused product, especially if other reliable evidence, such as schematics and technical documents, supports the expert’s conclusions.

The Federal Circuit thus vacated and remanded the case to the district court.