Stacey Anne Mahoney’s practice encompasses all aspects of antitrust law. In her antitrust litigation practice, she represents clients as plaintiffs and defendants in courts throughout the United States in cases involving restraints of trade, monopolization, price fixing, tying, exclusive dealing, price discrimination, false advertising, unfair competition, and related business torts. She has also litigated numerous complex commercial cases in federal and state courts across the country. In her merger practice, Stacey develops and implements domestic and international merger advocacy strategies, including trial as needed. Stacey’s counseling practice includes advising on distribution, employment, and pricing issues, as well as joint ventures and other competitor collaborations.
Stacey analyzes and designs antitrust compliance programs for domestic and international clients, and regularly represents clients before the US Department of Justice (DOJ), Federal Trade Commission (FTC), and states’ attorneys general in civil and criminal antitrust matters. She has worked extensively in pharmaceuticals and healthcare, payment systems, financial services, advertising and marketing, retail, and publishing.
Stacey is consistently ranked among the top antitrust lawyers in New York by Chambers USA and Super Lawyers, The Legal 500, and Global Competition Review. Chambers USA recognizes her “excellent antitrust litigation practice” and describes her as “very smart and very responsive,” and “very perceptive and very knowledgeable,” offering a “highly pragmatic approach to matters.” Super Lawyers reports that she is a “fearless and innovative litigator, able to adjust to any type of antitrust case,” who has “an outstanding ability to think strategically.” In 2019, Stacey was awarded the William T. Lifland Award bestowed in recognition of her role as a leading antitrust practitioner and her service to the broader antitrust community.
Stacey regularly writes and speaks on antitrust issues in the United States and abroad. She is a fellow of the Litigation Counsel of America and the American Bar Foundation. She is a past chair of the Antitrust and Trade Regulation Committee of the New York City Bar Association, and a former chair of the Antitrust Section of the New York State Bar Association.
Stacey clerked for Judge K. Michael Moore, now former-Chief Judge, in the US District Court for the Southern District of Florida from 1994 to 1996.
She serves on the Steering Committee for ML Women NY, is the co-chair of the ML First Generation Lawyers’ Network, was formerly the co-chair for the Morgan Lewis Return to Work Network, and was on the firmwide ML Women Steering Committee.
Antitrust and Commercial Litigation
Transactional Antitrust and Agency Advocacy
Counseling
Recognized, Antitrust Litigation, Lawdragon 500 Leading Litigators in America (2022, 2024, 2025)
Listed, The Best Lawyers in America, Antitrust Law, New York (2021–2025)
Member, Practice Group of the Year, Competition, Law360 (2017–2021)
New York State Bar Association
American Bar Association
New York City Bar Association
Women's Competition Network
Fellow, The American Bar Foundation (2016–present)
Fellow, Litigation Counsel of America (2015–present)
Recommended, Antitrust: Civil litigation/class actions: defense, The Legal 500 US (2020–2024)
Ranked, Antitrust, New York, Chambers USA (2010, 2013–2024)
Recognized, Litigation Star: Competition/antitrust, Benchmark Litigation (2022, 2024)
Recognized, William T. Lifland Award (2019)
Recognized, Metro Super Lawyers, Top 50 Women New York (2017–2022)
Recognized, US News & World Report and Best Lawyers 2017 Practice Group of the Year for Antitrust Law
Recognized, Super Lawyers, New York (2009–2024)
Recognized, Competition, Global Competition Review's Who's Who Legal (2015, 2018–2024)
Recognized, Irish Legal 100 (2015–2018); Antitrust Litigator of the Year: New York (2015)
Recognized, Legal 500 United States, Antitrust (2013–2015)
Recognized, LatinVex, Latin America's Top 50 Female Lawyers, only lawyer recognized for Litigation, Antitrust (2014)
2013 Law360 Competition Editorial Advisory Board
Recipient, 2016 Global Law Conference Antitrust Litigator of the Year
Recipient, Archibald R. Murray Public Service Award, Fordham University School of Law
Notes and Comments Editor, Environmental Law Journal, Fordham University School of Law