John F. O'Sullivan

"Easily straddles cultural divides and is on everybody's wavelength."

Chambers & Partners

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." Other clients note that he offers "brilliantly concise courtroom and written advocacy, and high-level strategic and tactical insight." He has more than 25 years of experience litigating a wide range of complex commercial matters.

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.

Numerous guides identifying top lawyers include John, such as Chambers USA, Best Lawyers in America, Super Lawyers, and Florida Trend's Legal Elite. John is also dedicated to pro bono; many legal services organizations have awarded and recognized him for his efforts on behalf of pro bono clients.

Awards and recognitions


Commercial Litigation
Best Lawyers in America


Litigation: Banking and Finance
Best Lawyers in America


Litigation: Real Estate
Best Lawyers in America

2009-2013, 2017-2020

Litigation: General Commercial (Florida)
Chambers USA

2008-2013, 2017-2020

Business Litigation
Florida Super Lawyers


Top Rated Lawyers, Commercial Bankruptcy Creditor-Debtor Rights


Super Lawyers: Corporate Counsel, Business Litigation

Outstanding Volunteer Lawyer Award
The Legal Aid Society


Most Valuable Protector (MVP) Award
Voices for Children, Inc.


Community Advocate of the Year
11th Judicial Circuit

Education and admissions


J.D., The George Washington University Law School, with honors, 1988

B.A., University of Massachusetts Amherst, cum laude, 1985

Economics & International Relations Program, University of Sussex, 1984


International Academy of Trial Lawyers, Fellow

University of Miami Center for Ethics and Public Service, Senior Fellow

University of Miami School of Law, Adjunct Professor

Bar admissions and qualifications


New York

Court admissions

U.S. Bankruptcy Court, Middle District of Florida

U.S. Bankruptcy Court, Northern District of Florida

U.S. Bankruptcy Court, Southern District of Florida

U.S. Bankruptcy Court, District of South Dakota

U.S. Court of Appeals, Eleventh Circuit

U.S. Court of Appeals, Second Circuit

U.S. Court of Appeals, Seventh Circuit

U.S. Court of Appeals, Federal Circuit

U.S. District Court, Middle District of Florida

U.S. District Court, Northern District of Florida

U.S. District Court, Southern District of Florida

U.S. District Court, Southern District of New York

U.S. District Court, District of Minnesota

U.S. Supreme Court

Representative experience

Secured dismissal of claims brought by Florida cities against banks seeking damages for lost tax revenue in litigation heard by the U.S. Supreme Court.

Prevailed in multi-jurisdiction litigation over ownership of real estate financial assets valued at nearly US$1bn.

Obtained preliminary injunction for life sciences client preserving more than US$1bn in sales.

Prevailed at trial for consumer products company in dispute over ownership of formulas for client's best-selling products.

Obtained dismissal with prejudice of securities claims seeking US$190m against a ratings agency alleging fraudulently inflated RMBS ratings.

Obtained one of the largest sanctions awards on record in Florida based on showing that principal of opposing party gave false deposition testimony.

Litigation counsel for clients in connection with many of the most prominent real estate assets in South Florida.

Established violation of the Federal Anti-Collusion Act and obtained dismissal of all claims against German financial services client.

Recovered more than US$25m for a Spanish client in disputes arising from a Florida acquisition.

Obtained a dismissal with prejudice for a major Japanese bank in a US$200m lender liability suit arising from Florida real estate investments.

Obtained a nationwide permanent injunction on behalf of a major broadcasting network in a copyright infringement suit against a satellite TV provider.

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