Leon B. Greenfield


Greenfield, Leon B.

Leon B. Greenfield has an exceptionally wide breadth of experience representing clients in complex antitrust-related matters. He has represented clients in cutting edge Section 2 litigation and agency matters. He has secured antitrust clearance for major acquisitions, litigated cases in federal and state court and counseled clients on many types of antitrust issues. Mr. Greenfield also has broad experience in matters outside the antitrust area, including securities regulatory matters and litigation and complex business litigation.


Many of Mr. Greenfield's recent matters have involved complex issues relating to monopolization allegations. Mr. Greenfield's practice also includes obtaining merger clearance for transactions in a diverse range of industries, including defense and aerospace, computer products, scientific equipment, agricultural and other chemicals, entertainment, professional services, airlines and financial services. Many of those transactions have required regulatory approval both in the United States and other countries.

Mr. Greenfield has also handled many civil non-merger competition matters, both in the United States and the European Union, and regularly counsels clients on antitrust matters. He has represented clients in a variety of securities, regulatory and litigation matters and has been involved in many litigation and major internal investigations in the defense and aerospace, securities and corporate governance areas.

Honors & Awards

  • Recognized as a leader in antitrust law in the 2008–2017 editions of Chambers USA: America's Leading Lawyers for Business
  • Recommended in the areas of antitrust litigation and merger control by The Legal 500 United States
  • Named to the 2012–2017 Washington DC Super Lawyers lists for his work in antitrust litigation
  • Listed in the 2014 edition of Expert Guides as a leading economist in Washington DC in the area of Competition/Antitrust Law
  • Listed as a leading competition/antitrust attorney in the 2007–2008, 2008–2009 and 2009–2010 editions of the PLC Cross-border Competition Handbook

Publications & News


December 6, 2017

WilmerHale Represents Regal Entertainment Group in Signing of Definitive Agreement to Be Acquired by Cineworld Group PLC

Regal Entertainment Group announced that it has entered into a definitive merger agreement with Cineworld Group PLC for Cineworld, the UK's largest cinema operator.

October 2, 2017

Wait, I Thought We Were Done? DOJ Challenges $4B Merger Months After HSR Filing and Expiration of the HSR Waiting Period

Earlier this week, the Antitrust Division of the Department of Justice filed a lawsuit seeking to unwind Parker-Hannifin's $4.3 billion consummated acquisition of Clarcor.

August 4, 2017

WilmerHale Represents Fortive in Acquisition of Industrial Scientific Corporation

On July 27, 2017, Fortive Corporation (NYSE: FTV) announced that it signed a definitive agreement to acquire Industrial Scientific Corporation, a leading provider of portable gas detection equipment and a safety-as-a-service pioneer.

June 9, 2017

The Legal 500 United States 2017 Recognizes 125 WilmerHale Lawyers Across 28 Practice Areas

The Legal 500 United States has released its 2017 rankings, recommending 125 WilmerHale lawyers—including 12 who are named to its elite “Leading Lawyers” list and two on its “Next Generation Lawyers” list—and 28 practice areas in its 11th edition.

May 30, 2017

The National Law Journal Names WilmerHale Washington DC Litigation Department of the Year

The National Law Journal has named WilmerHale the 2017 Washington DC Litigation Department of the Year in the General Litigation category.

May 26, 2017

WilmerHale Lawyers and Practices Recognized in 2017 Edition of Chambers USA

Chambers and Partners announced its rankings for the 2017 edition of Chambers USA: America's Leading Lawyers for Business, with WilmerHale listed among the nation's best in 50 practice area categories. Chambers also ranked 86 WilmerHale lawyers as leaders in their respective fields.

April 28, 2017

2017 M&A Report

Our 2017 M&A Report provides a detailed global M&A market review and outlook. Other highlights include takeover defenses for public companies; key lessons for buyers and sellers considering earnouts; recent developments in merger control regulation; common interest privilege protection among deal parties; special considerations in California M&A deals; acquisition financial statement requirements for IPO companies; a comparison of deal terms in public and private acquisitions; and key terms and issues in sales of VC-backed companies.

April 10, 2017

The Cambridge Handbook of Antitrust, Intellectual Property, and High Tech

WilmerHale Partners Leon Greenfield and Mark Ford authored the chapter "Walker Process and Sham Litigation" in The Cambridge Handbook of Antitrust, Intellectual Property, and High Tech. In the chapter, the authors discuss the history and development of the Walker Process and sham litigation doctrines, some of the key unresolved issues that courts struggle with today, and scholarship relating to these doctrines.

February 14, 2017

WilmerHale Counsels Cynosure in $1.65B Acquisition by Hologic

The WilmerHale team on the transaction was led by Hal Leibowitz and Jason Kropp and included Andrew Bonnes, Kim Wethly, Leon Greenfield, Bruce Manheim, Steve Barrett, Laura Schneider, Amy Null, Julie Hogan Rodgers, Ciara Baker, Davis Sluis, Caroline Dotolo and Alex Civetta.

January 24, 2017

Facelift for Two Millennials: DOJ and FTC Update Guidelines for IP Licensing and International Enforcement

Earlier this month, the Department of Justice and the Federal Trade Commission issued the very first update to their IP Licensing Guidelines since April 1995. The agencies also published updated International Antitrust Guidelines. This WilmerHale Client Alert was republished in The Licensing Journal.

Recent Highlights

  • Representing Intel Corporation in matters regarding high-tech products
  • Represented an international airline in connection with an agency investigation into alleged price fixing
  • Representing high-tech clients in litigation concerning standard-setting proceedings and other issues relating to intellectual property
  • Representing shipping companies in arbitration-related issues pending before the United States Supreme Court
  • Represented BAE Systems in obtaining antitrust clearance for its $4.2 billion acquisition of United Defense
  • Obtaining summary judgment on behalf of Regal Cinemas in litigation over alleged antitrust violations brought by a competing theatre owner
  • Represented Witness Systems in connection with its $950 million sale to Verint Systems in the call center software industry
  • Representing a seller in obtaining antitrust clearance in a major transaction in the computer security industry
  • Obtained antitrust clearance for a buyer in a major transaction in the healthcare information technology sector
  • Representing Regal Cinemas in obtaining merger clearance in various acquisitions
  • Represented a cellular telephone component producer in an antitrust counterclaim arising from patent litigation
  • Represented a scientific equipment manufacturer in a major acquisition
  • Represented four Austrian banks in obtaining dismissal of antitrust claims brought by an overseas purchaser in a case alleging fixing of rates for exchanges of European currency and gaining affirmance by Second Circuit on remand from Supreme Court
  • Secured antitrust clearance from the Federal Trade Commission for Bayer AG's $7 billion acquisition of Aventis CropScience, creating the world's second largest crop protection corporation

Professional Activities

Mr. Greenfield has taught courses on comparative competition law and international civil litigation at Georgetown University Law Center. He also speaks frequently and has participated in events such as the ABA Antitrust Section Spring Meeting, the ABA symposium on the Antitrust Modernization Commission at Mid-Course, the Penn State Law School Seminars, the IBA Antitrust Conference in Sydney, Australia, the Canadian Competition Invitational, and the British Institute of International Comparative Law's Workshops on International Cartels and Efficiencies in Merger Analysis. Mr. Greenfield also writes regularly on antitrust topics.

Mr. Greenfield is a Senior Editor of the Antitrust Law Journal. He is Co-Editorial Chair of the Section of Antitrust Law Mergers and Acquisitions, 4th edition (forthcoming). Mr. Greenfield previously served as the Editorial Board Chair of the 2009 Annual Review of Antitrust Law Developments and as a board member in 2007 and 2008.


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JD, with honors, University of Chicago Law School, 1989, Associate Editor, University of Chicago Law Review

BS, with honors, Pennsylvania State University, 1986

Bar Admissions

District of Columbia

Pennsylvania (Inactive)


The Hon. Stanley Marcus, US District Court for the Southern District of Florida, 1989 - 1990

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