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Irvine Office
Senior Associate
714.972.1404 fax
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Bar Admissions

  • California, 2011
  • District of Columbia, 2016
  • New York, 2017


  • University of Virginia School of Law (J.D., Order of the Coif, 2011)
    • Executive editor, Virginia Journal of Law and Social Policy 
    • Pro Bono Service Award
    • Paul A Simon Memorial Scholarship
  • University of California, Los Angeles, California (B.A. in Philosophy, summa cum laude, 2007)

Sean S. Twomey

Sean S. Twomey is a Senior Associate at the Irvine office of Murchison & Cumming, LLP, focusing his practice on professional liability. Sean has a proven track record of representing global Fortune 100 and 500 companies, including in the healthcare, defense, and retail industries, and serving as outside counsel for an international sports retail company with expertise advising clients on high-profile athlete endorsement contract negotiations.

Sean has a wide spectrum of experience including complex commercial cases, appellate law, sports law, and healthcare compliance and enforcement matters. His background includes managing internal investigations, compliance audits, False Claims Act qui tam litigation, and civil and criminal investigations related to defense export controls, and promotional, kickback, and safety issues involving FDA-regulated drug and devices. Early in his career, Sean won a high-stakes summary judgment on behalf of a well-recognized sports brand. The case involved a breach of contract and business tort lawsuit in which a sunglasses company sought over $100 million in damages after a professional athlete signed an endorsement agreement with his client.

Sean earned his law degree from the University of Virginia School of Law, where he was honored with the Order of the Coif and received the Paul A. Simon Memorial Scholarship and the Pro Bono Service Award for his academic achievements and pro bono work. He graduated summa cum laude with a bachelor's degree in philosophy from the University of California, Los Angeles.

For Sean, the most gratifying aspect of legal work has been his pro bono efforts on behalf of veterans seeking service-related medical benefits from the U.S. Department of Veterans Affairs (VA), particularly in federal court appeals. He developed and taught a litigation clinic for several years at University of California, Irvine School of Law, guiding students in handling these cases. Sean also took on numerous pro bono cases referred through The Veterans Consortium, a national pro bono veterans organization, while at his prior firm. These cases are special to Sean because his grandfather was a Marine Corps pilot who served in WWII and Korea, and received VA benefits. His dedication earned him the VIP Pro Bono award from the Veterans Consortium in 2018 and a Congressional Certificate of Special Recognition for his service to veterans in 2019.

When away from the office, Sean enjoys spending time with his son and enjoying the outdoors with his three dogs, gardening, and watching professional and college sports. One of Sean's core values is providing service to his community, with his family volunteering at various events and organizations in Orange County.

Honors and Awards

  •  Best Lawyers' 2022 Ones to Watch in Entertainment and Sports Law  


  •  Conversational Spanish

Professional Associations and Memberships

  • Served on the Law360 Sports Editorial Advisory Board from 2019-2020
  • Served on the Board of Directors for Veterans Legal Institute in Orange County, a pro bono legal provider for low-income veterans

Published Works

Representative Published Decisions

  • Oakley, Inc. v. Nike, Inc., and Rory McIlroy, 988 F.Supp.2d 1130 (C.D. Cal. 2013) 
  • Allergan, Inc., et. al. v Athena Cosmetics, Inc., et. al., 738 F.3d 1350 (Fed. Cir. 2013)
  • United States ex rel. McGrath v. Microsemi Corp., 140 F. Supp. 3d 885 (D. Ariz. 2015), aff’d 690 Fed. App’x 551 (9th Cir. 2017)
  • Havensight Capital LLC v. Nike, Inc., 891 F.3d 1167 (9th Cir. 2018)
  • Burkhart v. Wilkie, 971 F.3d 1363 (Fed. Cir. 2020)