William H. Rooney is a partner in Willkie’s Litigation Department and Co-Chair of the Antitrust & Competition Practice Group.  He practices all aspects of antitrust law, including cross-border matters, before the antitrust enforcement agencies and the courts.   Bill regularly handles mergers, investigations, litigations, and counseling under the United States antitrust law and collaborates with Willkie’s European competition team in cross-border matters.



In 2016, Bill was honored with the William T. Lifland Award by the New York State Bar Association’s Antitrust Section in recognition of his contributions and accomplishments in the field.

Bill is listed in numerous legal publications, including Chambers USA (from 2006 forward, currently Band 2), Who's Who Legal: Competition (2022), The Best Lawyers in America (2014-2023), Who’s Who in America (2022), Competition and Antitrust Expert Guide (2020), Legal 500 (2020), New York Super Lawyers – Antitrust (Metro Edition 2007-2021), LMG Life Sciences (2012-2020), and Lawyers of Distinction (2022).

Bill serves on the Executive Committee of the Antitrust Section of the New York State Bar Association and received the NYSBA’s William Lifland award in 2016. He regularly contributes to the thought leadership of the bar by organizing and participating in conferences on contemporary antitrust issues.  Bill is a former Chair of the Antitrust Section of the NYSBA and of the Committee on Antitrust and Trade Regulation of the Association of the Bar of the City of New York.  He is also a former Vice-Chair of Economics Committee of the Antitrust Section of the American Bar Association.  In 2015 and 2018, Bill served on Law360’s Competition Editorial Advisory Board.

  • Taking Innovation Seriously: A Dynamic Competition Model for Antitrust Law  Moderator – Columbia Business Law Review (August 2023)
  • William Howard Taft Lecture “Taking Innovation Seriously: A Dynamic Competition Model for Antitrust Law,” Moderator (November 2022)
  • Time for A New Sherman Act? The Debate on Antitrust Reform in Historical Perspective – Columbia Business Law Review (2022)
  • William Howard Taft Lecture “Do We Need a New ‘Sherman Act’: To What End, By What Means, For Whose Benefit?,” Moderator (November 2021)
  • Tracing the Evolving Scope of the Rule of Reason and the Per Se Rule – Columbia Business Law Review (June 2021)
  • William Howard Taft Lecture “À La Carte or Prix Fixe: Choosing Among Rules of Liability,” Moderator (November 2020)
  • NYSBA Antitrust Law Section Annual Antitrust Symposium – Reassessing the Consumer Welfare Model in the Age of Technology (March 5, 2020)
  • Assessing Qualitative Justifications Under Taft's Rule of Reason – Columbia Business Law Review (December 2019)
  • William Howard Taft Lecture "Balancing Unquantified Benefits and Harms Under the Consumer Welfare Standard," Moderator (September 2019)
  • Amex In Context: Tracing the Application of the Rule of Reason to Vertical Restraints – Columbia Business Law Review (March 2019)
  • William Howard Taft Lecture "After AmEx, Multi-Sided Markets, Anticompetitive Effects, and the Rule of Reason" (September 2018)
  • William Howard Taft, the Origin of the Rule of Reason, and the Actavis Challenge – Columbia Business Law Review (March 2018)
  • Next Generation of Antitrust Scholars Conference (January 2018)
  • NYSBA Antitrust Law Section Annual Antitrust Symposium – Multi-Sided Antitrust Markets: Smoke & Mirrors or Dynamic Competition?, Moderator (December 2017)
  • William Howard Taft Lecture “The Rule of Reason in the Post-Actavis World,” Moderator (September 2017)
  • ABA CLE in the City – Antitrust Track, Chair (August 2017)
  • GCR Antitrust Law Leaders’ Forum, Speaker – Dynamic Competition Means that Every Market Has Two Sides (February 2017)
  • NYSBA Antitrust Law Section Annual Antitrust Symposium – Third Time’s The Charm? Evaluating a Reimagined Staples Acquisition of Office Depot (December 9, 2016)
  • Staples II: Shifting Burdens and Unbalanced Equities – The Antitrust Counselor (September 2016)
  • ABA Section of Antitrust Law – Corporate Counseling Committee May Antitrust Update (June 9, 2016)
  • A Call for a New Antitrust Administration: A Holistic Assessment of Dynamic Competition -- Concurrences Review (2016)
  • NYSBA Annual Meeting, Moderator and Participant – Panel on Financial Benchmarks (January 2016)
  • O’Bannon v. NCAA: Reducing the Rule of Reason Analysis to Quantitative and Commercial Benefits – Euromoneys Competition and Antitrust Expert Guide (January 2016)
  • Getting Closer? The Application of Competition Laws to Regulatory Bodies in the U.S. and the EU – Journal of European Competition Law and Practice (January 2016)
  • NYSBA Annual Antitrust Symposium, Moderator – “Next Generation Rule of Reason: Metric of Methodology” (December 2015)
  • International Generics Association, Panelist – Presentation on Reverse Payment Settlements (September 2015)
  • NYSBA Antitrust Law Section Annual Fall Symposium, Organizer – “The Antitrust Implications of Conditional Sales” (November 2014)
  • GCR Antitrust Law Leaders’ Forum, Speaker – “4-to-3 Mergers and Their Competitive Effects – Do We Have a Better Understanding?” (February 2014)
  • Competition Policy Forum, Speaker – “Settling Patent Disputes in the Pharmaceutical Industry” (October 2013)
  • NYSBA Antitrust Forum, Organizer – “Upward Price Pressure, Market Definition and Supply Mobility" (October 2011)
  • “Reverse Payment Settlements in the United States and Europe: Moving Toward an Effects-Based Approach,” CPI Antitrust Chronicle (September 2013) (co-authored)
  • “Eleventh Circuit Rejects the Strength of a Patent as a Criterion for the Legality of Reverse-Payment Settlements,” CPI Antitrust Chronicle (June 2012) (co-authored)
  • “Lessons From Delta/AirTran and U-Haul: Charting Your Own Course and Exercising Discretion Pays Dividends and Avoids Antitrust Trouble,” The Antitrust Counselor (January 2011) (co-authored)
  • “Review of Reverse‐Payment Agreements: The Agencies, the Courts, Congress, and the European Commission,” Competition Policy International (Autumn 2009) (co-authored)


  • Cornerstone/ScionHealth
  • Warburg Pincus/DriveCentric
  • Wethersfield Institute/WICT
  • Trussway Industries/Builders FirstSource
  • AccessESP/Baker Hughes
  • Lynx FBO Holdings/KKR
  • The CapStreet Group/HungerRush
  • Arkema/Trinseo
  • Time Manufacturing/HIG
  • Frontline/PK Contracting; Specialized Pavement
  • SAP/Apax Partners (Signavio)
  • Polychem/CarbonLite
  • Time Manufacturing/Ruthmann
  • Highline/PPC
  • FIS/Worldpay
  • Constantia/Representation as Third Party in Multi-Billion Dollar Transaction
  • Silver Creek/Genesis
  • Constantia/Multi-Color Corporation
  • Bonduelle/ Ready Pac Foods
  • Dexko/KPS
  • Dormakaba/Stanley Black and Decker
  • Prime/DYK
  • FIS/SunGard
  • The Men’s Wearhouse/Joseph A. Bank
  • Hudson’s Bay Co./Saks Fifth Avenue
  • Seven Mile Capital Partners/Microporous
  • Bloomberg L.P./Bureau of National Affairs (BNA)
  • Teva/Cephalon (Europe)
  • Teva/Procter & Gamble (Europe –- OTC Joint Venture)
  • Teva/Lonza (Europe -- Biosimilar Joint Venture)
  • Teva/Ratiopharm
  • Teva/Barr
  • Pharmion/Celgene
  • TomTom/Tele Atlas
  • Mattel/Radica
  • Teva/IVAX
  • GameStop/Electronics Boutique
  • Teva/Sicor
  • Teva/Novopharm
  • CompUSA/Computer City
  • Loral/Orion
  • Loral/Skynet
  • Loral/Lockheed Martin
  • Mattel/Tyco
  • Mattel/Fisher Price

Investigations, Advocacy, and Litigation

  • Pulse Network LLC v. Visa Inc. (third-party representation)
  • Department of Justice cartel investigation
  • European Commission v. Teva (Perindopril)
  • European Commission v. Teva (Modafinil)
  • United States v. Aiyer
  • Two comment letters on proposed HSR rule changes (confidential clients)
  • U.S. v. Third Point Offshore Fund, Ltd.
  • Numerous agency antitrust investigations in the United States and Europe (confidential clients and subject matters)
  • High tech investigations in Europe, the United States, and Canada
  • Represent mining company in connection with joint venture
  • US v. Third Point LLC
  • In re Modafinil Antitrust Litigation
  • Apotex v. Teva Pharmaceuticals et al
  • In re Nifedipine Antitrust Litigation
  • In re ACR Tube Litigation
  • In re Copper Tubing Antitrust Litigation
  • Private Equity Antitrust Litigation
  • In re Insurance Brokerage Antitrust Litigation
  • In re Interchange Fee Antitrust Litigation
  • American Express v. Visa USA et al.
  • Teva Pharmaceuticals USA, Inc. v. FDA
  • Organon Sanofi-Synthelabo LLC v. Aventis Pharmaceuticals, Inc.
  • In re Nabumetone Antitrust Litigation
  • In re Options Exchanges Antitrust Litigation
  • Coalition for Level Playing Field Robinson-Patman Litigation
  • Intervest v. Bloomberg
  • Toys "R" Us Antitrust Litigation
  • Salomon Brothers Antitrust Litigation



Oxford University, Diploma in Law, 1987 Yale Law School, J.D., 1983 University of Notre Dame, B.A., 1980

Bar Admissions

District of Columbia, 1985 New Jersey, 1984 New York, 1984

Court Admissions

United States Supreme Court, 2002 United States Court of Appeals, 2nd Circuit, 2001 United States Court of Appeals, D.C. Circuit, 1984 United States District Court, District of New Jersey, 1984 United States District Court, Eastern District of New York, 1985 United States District Court, Southern District of New York, 1985


Tamm, Edward A., United States Court of Appeals, D.C. Circuit, 1983-1984