O’Melveny Worldwide

Sergei Zaslavsky

Partner

Washington, DC Office
Areas of Focus
Areas of Focus
Antitrust & Competition
Aviation
Litigation & Investigations
Overview Experience Insights News Credentials

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 synthesizes antitrust doctrine, economics, and facts into advocacy that is both rigorous and intuitive.

Sergei is a veteran of numerous federal trials and arbitration hearings. He has taken the testimony of executives and economic experts and has deposed numerous fact and expert witnesses. Sergei has obtained favorable verdicts for his clients in both bench and jury trials as plaintiff and defendant. In 2019, the National Law Journal named Sergei as a “DC Rising Star,” an award recognizing “the Washington, DC, region’s 40 most promising lawyers age 40 and under.”

In addition to his antitrust expertise, Sergei specializes in legal issues related to the burgeoning generative AI field, advising a major technology company on AI licensing issues and regularly writing and speaking on the issue.

Sergei has a diverse and deep set of experience, having worked on both litigation and regulatory matters, represented both plaintiffs and defendants, and put on both expert and fact witnesses. Within that broad set experience, however, there are areas where Sergei has developed particular expertise:

  • Merger Litigation. Sergei has taken part in six merger litigations. His accomplishments in this area include:
    • 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.” The representation received Global Competition Review’s 2018 “Merger Matter of the Year – Americas” award.
    • Represented US Airways in defending the merger with American Airlines against a DOJ challenge. The airlines settled the DOJ suit, allowing the merger to proceed and paving the way for the creation of the world’s largest airline. The representation garnered Global Competition Review’s 2014 “Matter of the Year” award.
    • Played a pivotal part in Honeywell’s challenge to Alarm.com-Icontrol merger, which resulted in favorable settlement for the client. Sergei was the principal drafter of the complaint and the briefing.
  • Two-sided markets. Sergei played a pivotal role in developing, preparing, and presenting the expert case in the US Airways v. Sabre litigation. The 2016 Sabre trial was the first district court case where two-sided platform doctrine played a key role after the Second Circuit’s Amex decision established the modern judicial approach to platform markets, and the 2022 trial was the first case after the 2018 Supreme Court Amex decision where evidence of net two-sided anticompetitive effects was presented to a jury. The O’Melveny team obtained favorable verdicts for its client US Airways in both the 2016 and 2022 trials. Sergei is one of the few lawyers to have both plaintiff and defense-side experience in two-sided market cases, giving him a comprehensive perspective on this important area of antitrust law. In 2023, Sergei published the Platform Antitrust Report, a comprehensive summary of legal developments in the law of two-sided markets.
  • Economic Experts. While Sergei has worked on virtually all aspects of antitrust litigation, he frequently focuses on the economic case. Sergei has taken the testimony of economic experts in federal court and has deposed both economic and non-economic experts.
  • Class Certification. Sergei has experience opposing class certification in antitrust cases in multiple jurisdictions and industries. In North Brevard County Hospital v. C.R. Bard, Sergei defeated class certification in a monopolization case and expunged hundreds of millions of dollars of potential liability. Sergei delivered the winning argument, persuading the district court judge that the class representative failed to present evidence capable of showing injury for any class member, let alone the thousands of hospitals it claimed to represent, and that the class representative was not a typical class member and not an adequate representative of the absent class members’ interests.

In addition to maintaining his busy and successful practice, Sergei is an active member of the antirust bar and regularly contributes thought leadership on cutting edge competition topics. Sergei has published approximately a dozen articles and has hosted dozens of podcasts on antitrust-related topics. Sergei is a member of ABA Antitrust Law Section Leadership (currently serving as Vice Chair of the Economics Committee) and a founding member of ABA’s Our Curious Amalgam podcast, a weekly program featuring interviews with leading antitrust and consumer protection thinkers and practitioners. Sergei has chaired and moderated panels at the last three ABA Spring Meetings (2024-2026).

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Get to Know Sergei

Get to Know Sergei

  • Representation of The Walt Disney Company in a series of class action lawsuits against streaming live pay TV subscribers, who allege that Disney’s licensing contracts and policies inflated prices for streaming pay TV packages.
  • Representation of The Walt Disney Company in litigation against DISH, defending Disney against DISH antitrust counterclaims alleging tying, attempted monopolization, and other claims.
  • Defense of 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. United States v. AT&T Inc., 310 F. Supp. 3d 161, 164 (D.D.C. 2018), aff’d sub nom. United States v. AT&T, Inc., 916 F.3d 1029 (D.C. Cir. 2019).
  • Defense of medical device company C.R. Bard in a tying case against competitor AngioDynamics. AngioDynamics sought over US$135 million (originally over US$260 million) in damages (pre-trebling) and an injunction forcing Bard to unbundle the technology it developed to help place catheters inside the patient. Following a three-week trial, the jury returned a complete defense verdict, finding that Bard was not liable for tying.
  • Representation of C.R. Bard in a tying class action brought by a hospital customer. Sergei delivered the winning argument in the District Court for the District of Utah, defeating certification and expunging hundreds of millions of dollars in potential liability.
  • Defense of RBC Capital Markets, LLC in a class action involving allegations of collusion to inflate interest rates on bonds, and related California False Claims Act case.
  • Advising a large technology firm on issues related to AI model licensing.
  • Advising a logistics company on AI policies.
  • Advising an AI industry collaboration on antitrust issues.
  • Preparation of key fact witnesses and second-chairing 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. US Airways, Inc. v. Sabre Holdings Corp., No. 11 CIV. 2725, 2017 WL 1064709 (S.D.N.Y. Mar. 21, 2017), remanded, 938 F.3d 43 (2d Cir. 2019). Sergei also helped prepare the economic case for the 2022 retrial that resulted in the first ever jury verdict finding that the defendant monopolized a two-sided market.
  • Defense of a major tech platform in a series of two-sided market monopolization and tying cases brought by various private and government plaintiffs.
  • Defense of US Airways - American Airlines merger.
  • Representation of Global Music Rights in antitrust litigation against the Radio Music Licensing Committee.
  • Defense of cryptocurrency pioneer Roger Ver and software developers in United American v. Bitmain, the first federal antitrust case involving cryptocurrency. The claims were dismissed with prejudice.
  • Representation of Honeywell in a lawsuit to block a merger between two competitors, resulting in a favorable settlement.
  • Representation of Honeywell in its acquisition of Intermec.
  • Representation a major electronics company in a high-stakes ICC arbitration, taking the testimony of high-ranking marketing executives and second-chairing expert examinations.
  • Representation of Sysco in a merger trial against the FTC.
  • Representation of a Fortune 100 Company in an FTC investigation relating to joint venture agreement and IP licensing issues. FTC dropped the investigation, allowing Sergei’s client to continue its joint venture.
  • Counseling of major clinical laboratory company on licensing issues.
  • Antitrust audit for Fortune 500 petrochemical company.
  • Representation of manufacturer of a weight loss product in an FTC Bureau of Consumer Protection investigation.

Admissions

Bar Admissions

  • District of Columbia
  • Maryland

Education

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

Honors & Awards

  • Recommended by The Legal 500 US for Civil Litigation/Class Actions: Defense (2023-2024, 2026) and Media & Entertainment: Litigation (2026)
  • Selected as one of The National Law Journal’s 2019 “DC Rising Stars”

Professional Activities

Member

  • ABA Antitrust Law Section Leadership
  • Vice Chair, ABA Antitrust Law Section Economics Committee
  • Founding Member, ABA Antitrust Law Section Our Curious Amalgam Podcast

Speaker

  • Session Chair and Moderator, ABA Antitrust Spring Meeting: Fundamentals – Economics (March 2026)
  • Session Chair and Moderator, ABA Antitrust Spring Meeting: Fundamentals – Economics (April 2025)
  • Session Chair and Moderator, ABA Antitrust Spring Meeting: New Frontiers in Market Definition (April 2024)
  • “Antitrust Year in Review and What to Expect in 2025,” O’Melveny Webinar (January 2025)
  • “Should Your Company Have an AI Policy?,” O’Melveny Webinar (January 2025)
  • “Trying and Winning a Two-Sided Market Case,” Level Legal Webinar (December 2024)
  • “Antitrust Enforcement in Artificial Intelligence: How Would Economists Regulate AI?,” ABA Webinar (October 2024)
  • “Debate on the Economics of Non-Compete Agreements and the FTC Ban,” ABA Webinar Debate (June 2024)
  • “Get Smart About Artificial Intelligence: We Help You Understand AI, its Opportunities, and its Legal Challenges,” O’Melveny Webinar (January 2024)
  • “Considerations for AI Regulation”, National Lieutenant Governors Association Business Meeting (December 2023)
  • ABA Fundamentals of Antitrust Economics Series: Statistical Significance (November 2018)
  • ABA Consumer Protection Update (October 2015)

Author / Co-Author

  • “The Market Definition Paradox: Qualitative Evidence Ascendant?” Antitrust, (Spring 2026) (with Patrick Jones and Adam Walker)
  • “Two Sides to Every Story: Trying and Winning a Two-Sided Market Case,” Antitrust (Spring 2024) (with Ian Simmons and Patrick Jones)
  • “A Counterfactual Analysis of Amazon’s Acquisitions Under the 2023 Merger Guidelines,” Review of Industrial Organization (August 2024) (with Edward Snyder and Ian Simmons)
  • “President Biden Issues Sweeping Executive Order on Artificial Intelligence,” O’Melveny Client Alert (November 2, 2023)
  • “US AI Regulatory Policy Update: White House Secures More Voluntary Commitments; Congress Holds Hearings and Continues to Mull Legislative Framework; Agencies Provide Guidance on Competition, Financial Markets, and Intellectual Property Issues,” O’Melveny Client Alert (August 1, 2023)
  • “US Government’s AI Policy Coming into Focus in Series of Recent Announcements,” O’Melveny Client Alert (May 15, 2023)
  • “A Sheep in Wolf’s Clothing: Predatory Pricing, Platform Antitrust, and the Risk of False Positives,” Competition Policy International (April 26, 2023)
  • “Advocacy Group Files Complaint Urging FTC to Halt GPT-4 Amid Growing Pressure to Regulate Generative AI,” O’Melveny Client Alert (April 4, 2023)
  • “Buyer Cartel Doctrine: Lessons From Labor Antitrust,” Competition Policy International (June 29, 2021)
  • “Merger Control and Privacy: The Right Tool for the Job?” The Deal (October 12, 2020)
  • “Chilling Tech M&A Could Hurt Competition,” Law360 (June 23, 2020)
  • “OpEd: M&A No Special Antitrust Concern During Downturns,” The Deal (May 13, 2020)
  • “Blockchain and Antitrust: How Counsel Can Mitigate Risk,” Bloomberg BNA (January 9, 2019)
  • “Deciding Between Bench and Jury Trial: Reflections After US Airways v. Sabre,” Antitrust (Fall 2017) (with Charles Diamond)
  • “Price Discrimination Markets in Merger Cases: Practical Guidance from FTC v. Sysco,” Antitrust (Fall 2016) (with Ian Simmons)

Contributing Author

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

Podcasts

These are illustrative examples; Sergei has co-hosted many additional podcast episodes

Merger Review

  • Our Curious Amalgam, “What’s New in US Vertical Merger Enforcement? A Look at the UnitedHealth-Change Merger Decision and Beyond,” Co-Host, ABA (December 12, 2022)
  • Our Curious Amalgam, “Who Is Ready for 2021? Year in Review: Part 1,” Host, ABA (December 28, 2020)
  • Our Curious Amalgam, “Breaking News Special: Draft Vertical Merger Guidelines,” Co-Host, ABA (January 21, 2020)
  • Our Curious Amalgam, “Can We Have Mergers Without Tears: Understanding the Basics of Merger Review” (interview with Mike Keeley), Co-Host, ABA (August 26, 2019)

Artificial Intelligence and Big Tech

  • Our Curious Amalgam, “Are Chatbots Protected? Analyzing Whether Section 230 Should Apply to Generative AI,” Co-Host, ABA (May 29, 2023)
  • Our Curious Amalgam, “Why Does it Matter? The Role of Big Data in Antitrust” (interview with Daniel Sokol), Co-Host, ABA (February 3, 2020)
  • Our Curious Amalgam, “Why the Techlash? Antitrust Policy and Big Tech” (interview with Hal Varian), Co-Host, ABA (November 11, 2019)

Class Actions and Civil Litigation

  • Our Curious Amalgam, “What is the Secret Sauce Behind Developing a Complaint” (interview with Melinda Coolidge) Co-Host, ABA (September 23, 2019)

Labor and Antitrust

  • Our Curious Amalgam, “What’s the Hubbub About No-Poach? Recent Antitrust Enforcement in Labor Markets,” Co-Host, ABA (March 29, 2021)
  • Our Curious Amalgam, “Who Does Antitrust Work For? An Exploration of Labor Antitrust,” Co-Host, ABA (November 2, 2020)

Global Antitrust Enforcement

  • Our Curious Amalgam, “Too Political or Not Political Enough? A Debate on the Relationship Between Antitrust Enforcement and Democracy,” Co-Host, ABA (May 22, 2023)
  • Our Curious Amalgam, “What’s Happening in Germany and Spain? Conversations With Competition Law Enforcers at the 2023 Spring Meeting,” Co-Host, ABA (May 15, 2023)

US Antitrust Enforcement Policy

  • Our Curious Amalgam, “Where Do We Draw the Line? The Intersection of the First Amendment and Antitrust Under the Noerr-Pennington Doctrine,” Co-Host, ABA (October 13, 2025)
  • Our Curious Amalgam, “Are You on Board With Section 8? A New Era of Enforcement Against Interlocking Directorates,” Co-Host, ABA (November 20, 2023)
  • Our Curious Amalgam, “Have We Been Down This Road Before? What History Can Teach Us About the Current Rethinking of Antitrust,” Co-Host, ABA (October 18, 2021)
  • Our Curious Amalgam, “Are We Witnessing a Revolution? Putting the Debate Over Antitrust Reform Into Context,” Co-Host, ABA (May 17, 2021)
  • Our Curious Amalgam, “What is the Relationship Between Privacy and Competition? A Conversation with Commissioner Noah Phillips,” Co-Host, ABA (August 10, 2020)
Related Practices
Antitrust & Competition
Antitrust Counseling & Compliance
Litigation & Investigations
Merger Clearance
Related Industries
Artificial Intelligence
Aviation