LAWYER PROFILE
Karen Kazmerzak

Karen Kazmerzak

USA 2026

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Ranked in 1 practice area

About

Provided by Simpson Thacher & Bartlett LLP

Practice Areas

A former Federal Trade Commission (FTC) lawyer, Karen Kazmerzak advises clients on a wide range of antitrust and competition issues, particularly in seeking clearance for high-profile, complex mergers and acquisitions before the Department of Justice and FTC, and in developing strategies to advocate for merger approval in international jurisdictions.

Recognized as a leader in the field by Chambers USA, Legal 500 and a “Litigation Star” by Euromoney’s Benchmark Litigation, she is lauded by clients as “a consummate advocate with an eye for detail and excellent relationships with the government” and a “natural choice for any company trying to get a tough deal through the FTC or DOJ." Karen is also recognized for her work representing third-party market participants in connection with opposition to acquisitions and in connection with government subpoenas.

Karen’s extensive private sector and government experience has spanned numerous industries, including the life sciences, energy, transportation, healthcare and telecom sectors, among many others. She also counsels clients on antitrust matters involving licensing, distribution, pricing and competitor collaborations.

Professional Memberships

Karen is an active member of the American Bar Association Section of Antitrust. She served as a vice chair of the Transportation and Energy Industries Committee (2012–2018) and currently serves as an associate editor of ANTITRUST. Karen is also a co-founder of the Women’s Antitrust Forum, an organization based in Washington, D.C.

Personal

University of Iowa College of Law, 2006 J.D.; University of Iowa, 1998 B.S., Microbiology.

Chambers Review

Provided by Chambers

Chambers Guide to the USA

Antitrust - District of Columbia

Band 4
Band 4

Individual Editorial
Karen Kazmerzak is recommended for her expertise in transactional antitrust matters, providing compliance counseling to prominent clients. She also handles the merger review process, notably representing third-party clients.

Strengths

Provided by Chambers

  • Karen is a sharp antitrust lawyer. She is really good at articulating the nuances to the business folks.

    AntitrustChambers Guide to the USA

Ranked Individuals at Simpson Thacher & Bartlett LLP (156)

California

California: Los Angeles & Surrounds

California: San Francisco, Silicon Valley & Surrou

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District of Columbia

Illinois

Massachusetts

New York

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