O’Melveny Worldwide

Antitrust & Competition

Combining deep antitrust know-how and trial prowess, O’Melveny defends clients facing complex private litigation and aggressive antitrust enforcement challenges. 

Making History: Six Strategic Trials in a Blockbuster Year of Antitrust Litigation

Combining deep antitrust know-how and trial prowess, O’Melveny defends clients facing complex private litigation and aggressive antitrust enforcement challenges. 

Making History: Six Strategic Trials in a Blockbuster Year of Antitrust Litigation

O’Melveny brings decades of sophisticated antitrust experience and trial credibility to the full suite of clients’ antitrust and competition-related needs. Whether advising a client facing scrutiny over an industry-shaping transaction, defending a company in high-stakes antitrust investigation, or helping a client fight class-action litigation, we approach every case with expertise, judgment, and ingenuity. We have achieved many “firsts” in antitrust litigation, guiding our clients through complex and constantly evolving laws to help them mitigate business risk and secure their most important objectives.

Perennially ranked among the top global antitrust practices by preeminent legal directories—including Chambers Global, Chambers USA, Global Competition Review, The Legal 500 US, Benchmark Litigation, and Law360—we have earned a reputation for sophisticated, practical antitrust strategy that combines innovative economic and doctrinal analyses with an adept reading of the regulatory and political environment. Our antitrust practice seamlessly integrates with O’Melveny’s corporate, intellectual property, employment, and appellate litigation teams to advise on US and international competition issues including:

  • Substantive defense of government review of transactions
  • Private antitrust and class action treble damage litigation
  • Cartel investigations and defense of cartel prosecutions
  • Defense of civil antitrust actions by government authorities
  • Government conduct investigations
  • Judicial review of government and agency decisions

Our team benefits from regulatory and policy insight with public enforcers like the US Department of Justice, the US Federal Trade Commission, US Attorney’s Offices, the European Commission, China’s State Administration for Market Regulation, the Hong Kong Competition Commission, and other agencies, many of whose staff are former colleagues of ours. Our government experience offers clients an invaluable perspective and helps us craft winning strategies.

Antitrust Litigation

Complex antitrust litigation is a hallmark of O’Melveny’s antitrust practice. Our first-chair antitrust litigators are some of the most experienced courtroom lawyers in the United States, with a strong track record of winning cases at trial and on appeal—a strength few antitrust practices can claim. Our abilities range from extricating clients early and efficiently to achieving groundbreaking results in matters of first impression. Our litigators have shaped several antitrust cases of first impression including:

  • Trying and winning the first US criminal antitrust case to be tried three times, United States of America v. Penn et al., 1:20-cr-00152 (D. Colo. 2022).
  • Trying and winning the first jury trial of a two-sided market, US Airways, Inc., for American Airlines, Inc. v. Sabre Holdings Corporation, et al., 1:11-cv-02725 (S.D.N.Y. 2022).
  • Successfully defending antitrust claims in the first US antitrust case involving cryptocurrency and blockchain, United Am. Corp. v. Bitmain, Inc., 530 F. Supp. 3d 1241, 1249 (S.D. Fla. 2021).
  • Successfully defending antitrust claims in the first antitrust reverse-payment case in the US involving biosimilars, In re Humira Antitrust, 465 F. Supp.3d 811 (N.D. Ill. 2020).
  • Successfully arguing that state antitrust laws are preempted by the Federal Aviation Act in what the Court of Appeals called “a case of first impression,” In re Air Cargo Shipping Services Antitrust Litigation, 697 F.3d 154 (2d Cir. 2012).
  • Winning the first antitrust vertical merger trial in the US in over 40 years, United States v. AT&T Inc., 310 F. Supp. 3d 161 (D.D.C. 2018).
  • Trying and winning the first US antitrust criminal case involving a wholly foreign price-fixing conspiracy resulting in a landmark result, United States v. Nippon Paper Indus, Co., Ltd., 62 F. Supp. 2d 173 (D. Mass. 1999).

Antitrust Investigations

We leverage a sophisticated team of former prosecutors and leaders in the antitrust bar to advise industry leaders entangled in high-stakes cartel and conduct investigations and enforcement actions, including those alleging price-fixing, anticompetitive conduct, and abuse of dominance. We guide clients from beginning to end, from agency query to resolution and through appeal when necessary. We represent clients before US federal and state antitrust enforcers, the European Commission, China’s State Administration for Market Regulation (SAMR), and the Korea Fair Trade Commission, in some of the highest-profile cross-border cartel, anticompetitive conduct, and abuse of dominance cases in recent years.

Global Reach

Europe. Operating at the EU’s political and legislative center since 2004, our lawyers focus on EU and national competition law, including on merger control, market power abuses and restrictive agreements; foreign direct investment and subsidies screening; and sector regulation. We represent clients in proceedings before the European Commission and national enforcers in Germany, the UK, and elsewhere.

Asia. With offices and expertise across East Asia, we advise clients facing antitrust and competition issues throughout the region. A recognized market leader in China with a 20-year history in the country, we have advised on the Anti-Monopoly Law since its introduction in 2008. Our Tokyo and Seoul offices also have a long history of representing companies before the Japan Fair Trade Commission, the Korea Fair Trade Commission, and other regulatory bodies in connection with cartel and criminal investigations, abuse-of-dominance issues, general antitrust compliance, and mergers.

American Airlines

Secured a win for what was previously US Airways in a closely watched re-trial of a landmark monopolization and rule-of-reason two-sided market case brought against travel-booking company Sabre Corp. After winning at trial in December 2016 on a Sherman Act Section 1 claim, the verdict was reversed on appeal based on the Supreme Court’s intervening 2018 decision in Ohio v. American Express. O’Melveny re-tried the case in 2022 and won again, this time on the Section 2 claim.

AT&T and Time Warner

As lead trial counsel for the parties in the DOJ’s challenge to the $85.4 billion merger—the first vertical merger challenge tried to verdict in the US in decades—we helped secure a “sweeping victory” for the defense.

BH Management Services

Representing one the largest US multifamily residential property management firms in the In re RealPage, Inc. Rental Software Antitrust Litigation, an MDL class action brought by different sets of multi-family property and student-housing property class plaintiffs. Plaintiffs allege a conspiracy involving over 40 property owners and managers to inflate apartment rents using shared data through a common revenue management software vendor. In December 2023, in a significant win where O’Melveny argued defendants’ joint motion to dismiss, the court dismissed the nationwide student-housing case in its entirety, with prejudice, holding that the student plaintiffs had failed to plead any viable antitrust claim.


Secured a win for the company and individual developers in the first federal antitrust complaint in the cryptocurrency field. The court dismissed the entire case with prejudice, a significant victory that made new law on the application of the Sherman Act to the cryptocurrency industry and other emerging markets.

C. R. Bard

Obtained a complete victory in a three-week jury trial in the Northern District of New York, defending a Sherman Act tying claim brought by AngioDynamics, Inc. The competing provider of medical devices claimed that C. R. Bard violated federal antitrust laws by tying the sale of its tip location system to its line of peripherally inserted central catheters, which allegedly prevented competition in the marketplace and limited patient access to alternate technologies.

C. R. Bard

Successfully defeated class certification in a follow-on class action brought by a Florida hospital purporting to represent thousands of hospitals nationwide that purchased Bard catheters. The judge agreed with virtually all points advanced by O’Melveny, resulting in the denial of certification and eliminating potential liability of several hundred million dollars for the client. This outcome is particularly significant given the rarity of class certification denials in antitrust class actions.

Endo Pharmaceuticals

Won a sweeping victory in an antitrust monopolization case alleging that an Endo subsidiary had prevented a competitor from entering the market for an emergency blood-pressure boosting drug by purportedly entering into certain exclusive supplier agreements. After the Third Circuit vacated and remanded the first summary judgment ruling, in October 2021 the district court granted a second summary judgment in our client’s favor, decisively ending the long-running dispute.

Jayson Penn

Secured an acquittal for the former Chief Executive Officer of Pilgrim’s Pride Corporation, the second largest US chicken producer, in a criminal antitrust case filed in the District of Colorado. The case made history as the first antitrust criminal case to be tried three times, the final time resulting in a full acquittal after a four-week jury trial and just one day of deliberations. Global Competition Review recognized the case as the 2023 “Antitrust Behavioral Matter of the Year.”


Represented Novartis in a cutting-edge antitrust Walker Process case in the Northern District of New York. Regeneron alleged that Novartis and co-defendant Vetter Pharma International GmbH sought to block or delay the launch of a Regeneron drug that competes with a Novartis product. Following our successful transfer of the case to the N.D.N.Y., the district court dismissed Regeneron’s antitrust claims with prejudice in February 2022.

Samsung Bioepis

Defended the company in In re Humira (Adalimumab) Antitrust Litigation (N.D. Ill.), the first “reverse-payment” litigation involving biologics and biosimilars. Purchasers of Humira, the world’s most successful drug, alleged that pharmaceutical manufacturers violated Sections 1 and 2 of the Sherman Act by preventing the launch of lower-priced “biosimilar” competitors. The district court granted in full defendants’ motion to dismiss, holding that the plaintiffs failed to plausibly allege an unlawful “reverse payment” or antitrust injury (unanimously affirmed by the Seventh Circuit in August 2022).

Samsung Electronics

Defeated a consumer class action alleging that Samsung and other companies had agreed to restrict their output of dynamic random access memory (DRAM) chips—a vital component of phones, computers, and other electronics—in an attempt to raise prices on downstream purchasers of the products. We led the defendants’ briefing through multiple rounds of motions to dismiss, which the judge granted. In March 2022, the Ninth Circuit unanimously rejected the indirect-purchase plaintiffs’ appeal, affirming dismissal of their complaint; this led the direct-purchaser plaintiffs to voluntarily dismiss their separate appeal.

Representative Clients
American Airlines
Asiana Airlines
Capital One Financial Corp.
C. R. Bard
Charles Schwab
Endo Pharmaceuticals
Global Music Rights
HID Global
Honeywell International
Mitsui & Co.
Norsk Hydro ASA
Quest Diagnostics
Rohm Co. and Rohm Semiconductor U.S.A. LLC
Royal Bank of Canada
Samsung Electronics Co. Ltd.
SK Hynix

“O’Melveny’s antitrust team is superb and second to none.”

Client Testimonial, The Legal 500 US, Cartel, Nationwide

“Sophisticated practice that combines cartel defence, criminal and civil litigation expertise with a highly capable transactional antitrust offering. Able to tap into global resources to advise on cross-jurisdictional competition matters for important clients. Equally capable of representing both defendants and plaintiffs in complex litigation.”

—Chambers Global, Antitrust: Cartel, US Offices

“Prominent antitrust team with comprehensive litigation expertise and a strong merger clearance practice, handling major global transactions. Represents numerous household-name clients in some of the biggest US and worldwide cases, including class actions and multidistrict litigation.”

—Chambers USA, Antitrust, Washington, DC

“O'Melveny has incredibly good lawyers, very smart, very thorough, very prepared, very collaborative, very effective in front of the jury and really good tactically and strategically.”

—Client Testimonial, Chambers USA, Antitrust: Cartel

Featured annually in Global Competition Review’s “GCR 100” highlighting the world's best 100 antitrust and competition firms

Behavioral Matter of the Year—Acquittals in Broiler Chicken Trials

—Global Competition Review (2023)

Competition/Antitrust Practice Group of the Year

—Law360 (2019)