John F. O'Sullivan

John O'Sullivan is a leading trial lawyer handling high-stakes business disputes for top global clients. Chambers and Partners describes him as a "strong presence" in the courtroom who is "brilliant at breaking down complex problems so they are easy to understand." Clients praise John’s "brilliantly concise courtroom and written advocacy, and high-level strategic and tactical insight" and describe him as “very thorough, super smart and easy to work with.” He has more than 25 years of experience litigating a wide range of complex commercial matters.

Best Lawyers in America recently named John its “Lawyer of the Year” for Litigation: Banking and Finance in New York City, 2022. John has also been named “Litigator of the Week” by The AmLaw Litigation Daily, for his work securing an injunction against the State of Florida barring enforcement of a Florida statute which prohibited his client Norwegian Cruise Lines from requiring vaccine documentation. John is a Fellow of the International Academy of Trial Lawyers, recognized as the most prestigious organization of trial lawyers in the world, and is included in all of the major guides identifying top lawyers. John is dedicated to pro bono: the Legal Aid Society, Voices for Children, and numerous other legal services organizations have recognized him for his efforts on behalf of pro bono clients.

Whether it's breach of contract and tortious interference claims or patent, trademark, and copyright litigation, John's vast experience helps him help clients. John also handles trade secret and Lanham Act actions; unfair competition, price fixing, and monopoly claims; and real estate, banking, and construction litigation. He is also actively involved in securities and corporate governance disputes and professional negligence and malpractice matters.

In addition to his law practice, John teaches Advanced Civil Procedure at The University of Miami School of Law and also serves as a Senior Fellow at the UM Center for Ethics and Public Service.

Prior to practicing, John served as a law clerk for the Honorable William H. Timbers on the United States Court of Appeals for the Second Circuit.