United States Court of Appeals for the Federal Circuit ______________________

FRAUNHOFER-GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG E.V., Plaintiff-Appellant

v.

SIRIUS XM RADIO INC., Defendant-Appellee ______________________

2023-2267 ______________________

Appeal from the United States District Court for the District of Delaware in No. 1:17-cv-00184-JFB-SRF, Senior Judge Joseph F. Bataillon. ______________________

Decided: June 9, 2025 ______________________

DAVID C. MCPHIE, Irell & Manella LLP, Newport Beach, CA, argued for plaintiff-appellant. Also repre- sented by REBECCA CARSON, BEN J. YORKS; GRANT WILLIS GABRIEL, Los Angeles, CA.

MARK BAGHDASSARIAN, Herbert Smith Freehills Kra- mer (US) LLP, New York, NY, argued for defendant-appel- lee. Also represented by ALAN ROY FRIEDMAN, SHANNON H. HEDVAT, TOBIAS B. JACOBY, JASON MOFF, GARY P. NAFTALIS. Case: 23-2267 Document: 49 Page: 2 Filed: 06/09/2025

2 FRAUNHOFER-GESELLSCHAFT v. SIRIUS XM RADIO INC.

______________________

Before LOURIE, DYK, and REYNA, Circuit Judges. LOURIE, Circuit Judge. This case returns after we previously vacated the dis- trict court’s grant of Sirius XM Radio Inc.’s (“SXM”) motion to dismiss for failure to state a claim. See Fraunhofer-Ge- sellschaft zur Förderung der angewandten Forschung e.V. v. Sirius XM Radio Inc., 940 F.3d 1372 (Fed. Cir. 2019) (“Fraunhofer I”). Now on summary judgment, the district court again entered final judgment in favor of SXM, con- cluding that Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.’s (“Fraunhofer”) claims for infringement of now-expired U.S. Patents 6,314,289, 6,931,084, 6,993,084, and 7,061,997 (“the asserted pa- tents”) are barred by equitable estoppel. Fraunhofer-Ge- sellschaft zur Förderung der angewandten Forschung e.V. v. Sirius XM Radio Inc., No. 17-cv-184, 2023 WL 4420414 (D. Del. July 10, 2023) (“Decision”). We reverse. BACKGROUND 1 Fraunhofer is a non-profit research organization based in Munich, Germany, that has spent decades developing and patenting various inventions relating to multicarrier modulation (“MCM”) technology. That technology is used for Digital Audio Radio Service (“DARS”), otherwise known as satellite radio. On March 4, 1998, Fraunhofer entered into an agree- ment (“the Master Agreement”) with WorldSpace Interna- tional Network, Inc. (“WorldSpace”), granting WorldSpace

1 Additional background can be found in Fraunhofer I. We recount the relevant facts here for convenience. Case: 23-2267 Document: 49 Page: 3 Filed: 06/09/2025

FRAUNHOFER-GESELLSCHAFT v. SIRIUS XM RADIO INC. 3

a “worldwide, exclusive, irrevocable license, with the right to sublicense,” to various of Fraunhofer’s patents directed to MCM technology, including those asserted here. J.A. 1629. Also in 1998, Fraunhofer began a collaboration with XM Satellite Radio (“XM”) to bring satellite radio to the United States. Because that work would require use of the MCM technology protected by the asserted patents, Fraunhofer told XM that, in light of the Master Agreement, XM would need to seek a sublicense to those patents from WorldSpace. That condition was made express in a Firm Fixed Price Contract (“FFPC”) between XM and Fraunho- fer. J.A. 1707. XM obtained the requisite “irrevocable” sublicense, J.A. 1638–58, and, with the help of Fraunhofer, incorporated the patented MCM technology into its satel- lite radio system, the XM DARS System, which it launched in 2001. Later, in 2008, XM, which had successfully developed the “high-band” XM DARS System, joined forces with Si