Jeffrey A. Leon

E-mail MeJeffrey A. Leon

Highland Park, Illinois
Jeff A. Leon is a partner at Quantum Legal LLC and head of the firm's class action antitrust practice.

Jeff has a broad and deep understanding of the antitrust laws gained from his eighteen years of practicing antitrust law first as an associate at Kirkland and Ellis (1991-1996), as an associate (1996-2000) and a partner at Winston & Strawn (2000-2007) and as a partner at Ungaretti & Harris (2007-2008).

From a trial perspective, Jeff is one of the most experienced antitrust lawyers in the country. Unlike most antitrust lawyers, Jeff has actually tried cases. Jeff has:     - defended ITW Corporation in a two and one-half month jury trial against claims it had engaged in a conspiracy to fix the prices of high pressure laminate, gaining a complete defense verdict in favor of his client. The class in that case was seeking $1.3 billion in damages;     - defended Chicago Bridge & Iron in a three-month bench trial at the Federal Trade Commission against a challenge to its acquisition of Pitt-Des Moines, Inc.;     - defended Yukon Fuel in a contested consent decree proceeding and temporary restraining order hearing concerning its merger with its largest competitor, defeating challenges to the merger in both proceedings.
Jeff now uses his unique perspective as an experienced trial lawyer and defense lawyer to vindicate the interests of those aggrieved by anticompetitive conduct including price fixing, monopolization, and unlawful mergers and acquisitions. Jeff understands keenly how lawyers for these large companies will defend their clients, because he used to be one of those lawyers. He also understands how to prepare a case for trial, and is not afraid to see a case end up in a trial if a trial benefits his clients.
Jeff has written and spoken on antitrust issues. He has lectured on antitrust law at the Kellogg School of Business at Northwestern and he has published several articles on antitrust law including, for example, DISAGGREGATION OF ECONOMIST LIABILITY TESTIMONY IN SECTION ONE LITIGATION, ABA Section of Antitrust Law Economics Committee Newsletter and THE EVIDENTIARY ROLE OF ANTITRUST COMPLIANCE POLICIES IN SECTION ONE CIVIL LITIGATION, ABA Sherman Act Section One Committee Newsletter. Click here for a copy of some of Jeff's published articles. Jeff is a 1991 summa cum laude graduate of the Indiana University School of Law where he was third in his class, editor of the INDIANA LAW JOURNAL, champion of the Sherman Minton Moot court competition and a member of ORDER OF THE COIF. Jeff graduated cum laude from the University of Redlands in 1987 with degrees in political science and history. Jeff was a championship debater at Redlands , and was selected as the fifth most outstanding individual speaker at the 1987 National Debate Tournament.

Litigation Percentage

  • 100% of Practice Devoted to Litigation

Bar Admissions

  • Illinois, 1991
  • U.S. District Court Northern District of Illinois, 1991


  • Indiana University School of Law, Bloomington, Indiana
    • J.D. summa cum laude - 1991
    • Honors: Order of the Coif
    • Honors: Winner of the 1990 Sherman Minton Moot Court
    • Law Journal: Indiana Law Journal, Managing Editor, 1990 - 1991
    • Law Journal: Indiana Law Journal, 1989 - 1991
  • University of Redlands, Redlands, California
    • B.A. cum laude - 1991
    • Major: Political Science and History

Past Employment Positions

  • Kirkland & Ellis, Associate, 1991 - 1996
  • Winston & Strawn, Associate , 1996 - 2000
  • Winston & Strawn, Partner, 2000 - 2007
  • Ungaretti & Harris, Partner, 2007 - 2008


  • Alpha Gamma Nu