John F. O'Sullivan

John F. O'Sullivan: Leading Trial Lawyer in New York City

John F. O'Sullivan is a distinguished trial lawyer with over 25 years of experience handling complex business disputes for top global clients. Chambers and Partners has described him as a 'strong presence' in the courtroom who can brilliantly break down intricate legal issues into understandable terms. Clients have praised O'Sullivan's ability to provide both compelling courtroom advocacy and high-level strategic insight, describing him as thorough, smart, and easy to work with.

Practice Areas

• Litigation - Banking and Finance
• Commercial Litigation
• Litigation - Real Estate
• Litigation - Intellectual Property
• Mergers and Acquisitions
• Trade Secrets
• Lanham Act Actions (Trademark)
• Unfair Competition
• Price Fixing
• Monopoly Claims
• Real Estate Litigation
• Breach of Contract and Tortious Interference Claims
• Securities Disputes
• Corporate Governance Disputes
• Professional Negligence and Malpractice Matters
• Securities Disputes
• Banking Litigation
• Construction Litigation
• Intellectual Property Litigation (Patent, Trademark, Copyright)
• Real Estate Transactions and Disputes
• Breach of Contract Claims
• Tortious Interference with Business Relationships Claims

Awards and Recognitions

• Litigator of the Week by The AmLaw Litigation Daily (2021)
• “Lawyer of the Year” in Litigation: Banking and Finance, New York City (2026), 2024, 2022
• Best Attorney USA (Recognized since 2010)
• Litigation: General Commercial - Chambers USA (2009-2013, 2017-2021)
• Business Litigation - Florida Super Lawyers (2008-2013, 2017-2020)
• Community Advocate of the Year - 11th Judicial Circuit (2008)
• MVP Award from Voices for Children, Inc. (2008)
• Owen Thomas Honors Scholar - George Washington University School of Law (JD Class of 2004)
• William & Mary Foundation Award for Academic Excellence and Athletic Achievement in NCAA Division I Women's Volleyball
• Burnside Scholarship, Yale University (BA Degree) (2000)
• Recipient of the Presidential Scholarship from Yale College (Class of 1996)

Affiliations and Professional Experience

• Mentor and Advisor to Law Students - Columbia University, New York University School of Law, Fordham University School of Law, and Yeshiva University Benjamin Cardozo School of Law (Summer Fellows Program)
• Editorial Consultant for Legal Journal Articles

In addition to his extensive legal practice, O'Sullivan also serves as a mentor and advisor to law students in various programs. He has been involved in editorial consulting projects for legal journal articles.