Shaun P. Mahaffy

Shaun P. Mahaffy is a Partner at Williams & Connolly LLP, specializing in high-stakes patent litigation within the pharmaceutical and biotechnology sectors. His practice predominantly involves Biologics Price Competition and Innovation Act (BPCIA) and Hatch-Waxman litigation, representing clients in district court and Federal Circuit appeals, as well as in inter partes review (IPR) proceedings before the Patent Trial and Appeal Board (PTAB). Mahaffy's work centers on complex cases involving biologic products and small-molecule drugs.

Mahaffy primarily represents plaintiffs, as evidenced by his four tracked appearances on the plaintiff side. He has notably served as lead counsel for Regeneron Pharmaceuticals, Inc., in extensive BPCIA litigation concerning its blockbuster vision-saving biologic product, Eylea® (aflibercept). This included cases against Mylan Pharmaceuticals Inc. et al., Celltrion, Inc., and Sandoz Inc.. While one entry in the provided case list suggests a defendant role for Regeneron in a case against Sandoz Inc., public records consistently show Mahaffy representing Regeneron as the plaintiff in these disputes, challenging biosimilar applicants. His experience also includes representing Teva's Branded Division and Merck in Hatch-Waxman patent litigation and related IPRs, often in a plaintiff-oriented capacity.

Significant outcomes in which Mahaffy has been involved include securing a first-of-its-kind trial victory for Regeneron in its BPCIA litigation for Eylea®, which was the first BPCIA case tried to judgment in approximately five years. He was also part of the Regeneron team that reached settlements with Mylan, Celltrion, and Sandoz concerning Eylea biosimilars, often following successful preliminary injunctions or appeals at the Federal Circuit. He has also represented bioMérieux in patent litigation related to HIV diagnostic kits.

Shaun P. Mahaffy earned his J.D. from Yale Law School in 2013, a Ph.D. in Neuroscience from the University of California San Diego in 2010, and a B.A., summa cum laude, from Vanderbilt University in 2005. He clerked for the Honorable Ellen S. Huvelle of the U.S. District Court for the District of Columbia and the Honorable Paul V. Niemeyer of the U.S. Court of Appeals for the Fourth Circuit. He is admitted to practice in California.