Sergei Zaslavsky


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Sergei Zaslavsky is an antitrust attorney with broad experience in trials, regulatory merger reviews, conduct investigations, antitrust audits, and antitrust counseling. Sergei effectively represents his clients by being both detail-oriented and strategic, and by studying his clients’ businesses to understand how legal questions intersect with marketplace realities. In doing this, he is able to synthesize antitrust doctrine, economics, and facts into advocacy that is both rigorous and intuitive.

Sergei is a veteran of three federal trials and one arbitration hearing. He has taken the testimony of executives, second-chaired direct and cross examinations of world-famous economists, and argued in court. In 2018, Sergei was a key member of the O’Melveny AT&T-Time Warner merger trial team that prevailed against the DOJ in what the press has dubbed “the antitrust trial of the century.”


Honors & Awards

  • Selected as one of The National Law Journal’s 2019 “DC Rising Stars”


Bar Admissions

  • District of Columbia
  • Maryland


  • Harvard University, J.D.: magna cum laude
  • Dartmouth College, A.B., Economics: summa cum laude

Professional Activities


  • ABA Antitrust Section


Contributing Author

  • Antitrust Law Developments Update, ABA (2019)
  • Consumer Protection Law Developments, ABA (2016)


  • “Deciding Between Bench and Jury Trial: Reflections After US Airways v. Sabre,” Antitrust (Fall 2017)
  • “Price Discrimination Markets in Merger Cases: Practical Guidance from FTC v. Sysco,” Antitrust (Fall 2016)


  • Antitrust Law Section’s “Our Curious Amalgam - What’s The State of Things: 3 Things I Keep, 3 Things I Change (with Josh Wright),” Co-Host, ABA (2019)
  • Antitrust Law Section’s “Our Curious Amalgam - A Jargon-Free Overview of US Merger Control,” Co-Host, ABA (2019)
  • Antitrust Law Section’s “Our Curious Amalgam - Shepherding a Merger from Inception to Approval,” Co-Host, ABA (2019)


  • ABA Fundamentals of Antitrust Economics Series: Statistical Significance (November 2018)
  • ABA Consumer Protection Update (October 2015)
  • Defended AT&T and Time Warner against DOJ’s challenge of their historic merger. The trial was characterized as a “sweeping victory for AT&T” by The Wall Street Journal, and the representation received Global Competition Review’s 2018 “Merger Matter of the Year – Americas” award.
  • Represented a major electronics company in a high-stakes ICC arbitration, taking the testimony of high-ranking marketing executives and second-chairing expert examinations.
  • Prepared key fact witnesses and second-chaired economic experts’ direct and cross examinations in US Airways v. Sabre, an eight-week trial that resulted in a favorable jury verdict and garnered Global Competition Review’s “Litigators of the Week” award for the O’Melveny trial team.
  • Represented US Airways in litigation against the DOJ in its merger with American Airlines. The representation garnered Global Competition Review’s 2014 “Matter of the Year” award.
  • Represented Honeywell in its lawsuit to block competitors’ merger.
  • Represented Honeywell in its acquisition of Intermec.