Patrick E. O’Shaughnessy

A listen first and customer service focused business litigation attorney and practical problem solver for clients with legal challenges in myriad industries, including healthcare, insurance, financial services, and computer software


Whether the legal challenges with which you need help require counseling, in-court representation, or another means of dispute resolution, Patrick has meaningful experiences and uncommon perspective to share to help inform your business decisions. He has extensive substantive antitrust experience, with a focus on the analysis and proof or defense of antitrust liability and the evaluation of strategic business conduct in all types of antitrust cases. Patrick’s antitrust work in enforcement and private practice, for plaintiffs and defendants, as a counselor and a litigator, and at the federal and state level, in jurisdictions throughout the country, provides him with unique and broad-based insights that he uses to help clients find practical solutions to real-world problems

Patrick’s business litigation and counseling experience includes not just antitrust but also other types of business disputes, including breach of fiduciary duty and breach of contract disputes, most often in connection with business ownership disputes. He also has significant experience in IP/antitrust analysis and trade secret and copyright disputes

Despite his zeal for the courtroom, Patrick’s approach is customer-service focused. He emphasizes practical and client-centered business solutions. Many of his most gratifying accomplishments as a lawyer involve engagements where his clients do not appear in court

Previously, Patrick served in private practice in San Francisco, California, Columbus and Dayton, Ohio, and Washington, DC, and in government enforcement in Washington, DC as a Trial Attorney at the U.S. Department of Justice, Antitrust Division, which he joined through the Attorney General’s Honors Program, and in Columbus, Ohio as a Senior Assistant Attorney General at the Ohio Attorney General’s Office, Antitrust Section. While at the U.S. Department of Justice, Patrick was selected to serve as a Special Assistant United States Attorney for the U.S. Attorney’s Office in the Eastern District of Virginia and also as a Special Assistant for the U.S. Department of Justice, Antitrust Division’s Directors of Civil and Criminal Enforcement

Patrick grew up in Columbus, Ohio and proudly considers himself a Buckeye. He enjoys spending time with his family, following his longtime favorite Los Angeles Lakers, going to baseball games, and playing golf in the Bay Area as often as possible

Get in Touch

Patrick welcomes the opportunity to speak with you. O’Shaughnessy Legal Counsel typically charges an hourly rate for his time that depends on the nature of the work provided and is open to alternative fee arrangements, depending on the context

Recent Writing

Labor market criminal antitrust offenses in the crosshairs, Los Angeles & San Francisco Daily Journal (2021) (co-authored with Jack McLean)

Divided. Will conquer? Google faces 3 distinct challenges to its conduct, Los Angeles & San Francisco Daily Journal (2020)

U.S. allegedly to sue Google in rare antitrust lawsuit; if true, Google likely to lose, Los Angeles & San Francisco Daily Journal (2020)

Analyzing Ixchel v. Biogen’s new rules, Los Angeles & San Francisco Daily Journal (2020) (co-authored with Jack McLean)


UCLA School of Law, JD 2001
• Editor-in-Chief, Journal of International Law and Foreign Affairs
• Best Moot Court Team, Distinguished Advocate, and Outstanding Brief Writer Awards
• National Moot Court Team

Cornell University, BA 1998 cum laude
• Major in Economics
• Major in Government
• Varsity Letterman, Football

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