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Antitrust Litigation & Counseling

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WHAT WE DO

Our international reputation for excellence is based on successes in numerous high-profile antitrust cases. We were founded in 1994 as a boutique antitrust firm, and maintain our commitment to antitrust today.

We remain best known for our record-breaking accomplishments on behalf of plaintiffs. We nonetheless have substantial experience representing defendants — from Fortune 500 companies to small, family firms — in antitrust and commercial litigation.

OVERVIEW OF OUR EXPERIENCE

  • We secured a $3.05 billion settlement (plus injunctive relief valued at between $25 and $87 billion) as lead counsel to a class of millions of retailers in their payment card tying claims against Visa and MasterCard.
  • We secured a $2.75 billion settlement on behalf of Discover Financial Services in a case challenging Visa’s and MasterCard’s exclusionary rules prohibiting U.S. member banks from issuing Discover credit and debit cards to their customers.
  • We have represented parties successfully in jury trials and antitrust cases.
  • We represent plaintiffs and defendants in some of the country’s largest current commercial antitrust cases.
  • We represent parties advocating for or challenging transactions and/or business practices before federal and state antitrust enforcement agencies.
  • We represent parties to multi-billion dollar transactions in merger review proceedings before federal antitrust enforcement agencies.
  • We counsel companies on all aspects of antitrust, including antitrust compliance programs, distribution arrangements, licensing agreements, agency business reviews, merger analysis, litigation risk assessment as well as issues related to standard setting groups and the interface between intellectual property and antitrust law.
  • We submit amicus curiae briefs on important antitrust issues to the United States Supreme Court and to appellate courts.

INDUSTRY EXPERTISE

Constantine Cannon has litigated and counseled clients on antitrust matters that are relevant to a number of industries.

Among other things, Constantine Cannon has particular experience representing parties that participate in the following industries:

What Sets us Apart

Our attorneys are both experts in antitrust law and seasoned litigators. Our approach to every case, whether on the plaintiff’s side or the defense, is to be prepared to take the case to trial. Through technology, optimization of resources, and the specialized expertise of CAAS LLC, a consulting entity with which the firm has an existing relationship, we are able to contain the rapidly increasing costs of litigation better than other firms.

Counseling, Training and Investigations

Our counseling services include advising clients on the antitrust issues raised by certain business practices; enforcement agency investigations and business reviews; litigation risk assessment; merger analysis; management and employee training; advice on competitor collaborations, including joint ventures, standard setting organizations, and trade associations; and investigations into alleged antitrust violations.

Richard M. Aborn
New York
Gordon Schnell
New York
Steve Cannon
W. Stephen Cannon
Washington D.C.
Lloyd Constantine
Lloyd Constantine
New York
Owen Glist
New York
Seth D. Greenstein
Washington D.C.
Ankur Kapoor
New York
Jean Kim
New York
Marlene Koury
San Francisco
Gary J. Malone
New York
Alysia A. Solow
New York
Daniel Vitelli
New York
Robert L. Begleiter
New York
Allison F. Sheedy
Washington D.C.
Taline Sahakian
New York
Noah Brecker-Redd
New York
Hendrik Lammers
Washington D.C.
Jan Friedman Constantine
New York
Gary Reilly
New York
Richard O. Levine
Washington D.C.
Attorney Sarah Bayer Headshot
Sarah Bayer
New York
Attorney Janice Johnson Headshot
Janice Johnson
Washington D.C.
Michelle A. Peters
New York
Alan H. Schwartz
New York
Deborah Givens
New York
Matthew Koenig
New York
Osob Samantar
Washington D.C.
Patrick Kennedy
Patrick Kennedy
Washington D.C.
Dan Noel headshot
Dan Noel
San Francisco

Antitrust Today Blog Posts

Jun042026
Constantine Cannon LLP and Partners Ankur Kapoor and Gordon Schnell Named in Chambers USA 2026 Guide

By Constantine Cannon LLP Constantine Cannon LLP is delighted to announce our ranking as a Leading Firm in the Chambers and Partners USA Guide, 2026....

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Jun012026
Constantine Cannon Filed Amicus Brief on Behalf of Six Professors of Economics Supporting FTC’s Appeal in Case Against Meta

By the Constantine Cannon Antitrust Team In the FTC's appeal of the trial court's judgment for Meta Platforms, Ankur Kapoor and Ethan Litwin submitted an amicus...

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May062026
Constantine Cannon Files Amicus Brief Supporting Anthropic in AI Copyright Case

By the Constantine Cannon Antitrust Team On April 27, 2026, Constantine Cannon partner Seth Greenstein filed an amicus brief[1] on behalf of technology innovation advocacy groups...

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May052026
Constantine Cannon Wins Summary Judgment, then $14 Million Settlement for HDMI Licensing Administrator Inc. in License and Antitrust Dispute

By the Constantine Cannon Antitrust Team Constantine Cannon successfully defended the licensor of the HDMI interface technology, HDMI Licensing Administrator, Inc. (“HDMI LA”), against a...

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