Carrie Mahan

CARRIE MAHAN, a Chambers USA-ranked antitrust litigator and a trusted corporate counselor and risk advisor, has a diverse practice advising global companies on antitrust and consumer protection issues in both the government investigations and private litigation contexts, as well as in connection with mergers, acquisitions, and joint ventures.

Carrie partners with clients to guide their strategic business decisions, manage risks arising from pricing decisions, technology, customer and vendor relationships, overall marketplace direction, and improve and oversee compliance programs. Her clients value her pragmatic advice and creative thinking informed by decades of experience navigating them through bet-the-business and other crisis situations.

She has extensive experience representing clients in all major antitrust venues, including both state and federal courts and before federal, state, and international competition and consumer protection enforcement agencies, including the U.S. Federal Trade Commission, the Antitrust Division of the U.S. Department of Justice, and state attorneys general.

In court, clients look to Carrie to lead their defense and overall strategy, particularly as part of joint defense groups, owing to her proven ability to develop novel arguments to counter complex antitrust theories. For example, recently, she was appointed as liaison counsel for all 20 defendants in the dozens of federal antitrust class actions and direct action complaints in the consolidated litigation, In re Broiler Chicken Antitrust Litigation. She has secured victories at every critical stage of major nationwide antitrust class actions and multi-district litigations, including winning dismissals without discovery at the Rule 12 stage, defeating class certification, and prevailing at summary judgment. Additionally, Carrie has orchestrated favorable settlements in these matters that have significantly limited corporate liability and reputational harm.

In the regulatory, investigations, and transactional contexts, Carrie works closely with clients to secure approvals of proposed mergers, acquisitions, and joint ventures from the DOJ and the FTC, as well as favorably resolve, without litigation or public disclosure, non-public FTC investigations into trade association and joint venture conduct and activities. She also represents clients in criminal investigations before the Antitrust Division, including a recent grand jury investigation involving the media industry.

Carrie is well regarded in the market for her ability to consistently excel in high-stakes engagements. Most recently, Carrie was again included in Global Competition Review’s highly selective “Women in Antitrust 2025” list, naming her as one of the world’s foremost female leaders in antitrust and competition law—an honor given to only a select few. In 2024, she was named to Forbes’ inaugural “America’s Top 200 Lawyers” list, which spotlights the finest practitioners in the legal profession. Chambers USA recognizes Carrie among the top antitrust litigators in Washington, D.C., which calls out her leading “skills in class action defense,” and highlights client feedback touting her “incisive leadership as defense liaison counsel,” calling her “very smart, very focused,” and noting “she takes no prisoners.” She has also been recognized in Lawdragon’s “500 Leading Litigators in America” list every year since its inception. Additionally, Carrie has been selected to serve on Law360’s Editorial Advisory Boards twice, for Hospitality (2021) and Competition (2025), respectively.

• Representing Accor in a number of major class actions, including:
  • An antitrust class action filed in the U.S. District Court for the Northern District of Illinois alleging that Accor and other luxury hotel defendants engaged in a nationwide conspiracy to raise the price of rooms in luxury hotels in metropolitan markets across the country through the use of an algorithmic pricing platform. Specifically, Plaintiffs’ claim that Defendants’ access to the platform is conditioned on an individual hotel providing its own forward-looking demand data to competitors through the platform.
  • An antitrust class action filed in the U.S. District Court for the Western District of Washington alleging that the defendants violated Section 1 of the Sherman Act by exchanging competitively sensitive information through a third-party intermediary, which resulted in higher prices for luxury hotel rooms.
• Representing Wolters Kluwer N.V. in a putative antitrust class action filed in the U.S. District Court for the Eastern District of New York alleging that the world's six largest for-profit publishers of peer-reviewed scholarly journals, as well as an international trade association, unlawfully appropriated billions of dollars through a conspiracy to fix the price of peer review services at zero and to not compete on author manuscript submissions by prohibiting simultaneous submissions to multiple journals.
• Representing a multinational electronic commerce company in an antitrust class action alleging that the client used exclusivity restrictions to maintain its dominance in the audiobook market.
• Represented Hilton in a number of major class actions, including:
  
  • a nationwide antitrust class action filed against Hilton and other major hotel chains, in which class plaintiffs and an online travel company alleged that the defendant hotel companies conspired to eliminate competition for branded keyword search advertising against each other, eliminating competition among online travel agencies illegally raising consumers’ costs to find and book hotel rooms, seeking damages and injunctive relief under the Sherman Act.
  • a multidistrict antitrust class action filed in the U.S. District Court for the Northern District of Texas challenging alleged agreements between online travel companies and hotels regarding the retail prices for online hotel room reservations. Carrie secured the dismissal for Hilton on a Rule 12 motion to dismiss.
  • a lawsuit filed by an online travel company against Hilton and other major hotel chains in the U.S. District Court for the Eastern District of Texas alleging violations of the Sherman Act.
• Represented Pilgrim’s Pride as lead counsel in a number of significant litigations, including:
  
  • a purported nationwide class action brought by poultry complex workers alleging a conspiracy amongst poultry producers to reduce wages and limit competition for poultry complex workers. Carrie negotiated an early favorable settlement, with only limited discovery.
  • a series of federal class actions and direct action complaints brought by direct and indirect purchasers across the country alleging the major poultry producers reduced output to raise the price of broiler chickens, which were consolidated in the U.S. District Court for the Northern District of Illinois. Carrie resolved billions of dollars in claims and was selected to serve as liaison counsel for all 20 defendants named in these matters.
  • a series of nationwide class actions consolidated as an MDL in the U.S. District Court for the Eastern District of Oklahoma alleging poultry producers conspired to anti-competitively lower compensation to growers, in violation of the Sherman and Packers & Stockyards Acts.
• Represented Michael Foods, Inc. in resolving all claims related to an MDL by nationwide consumer classes and direct action plaintiffs, alleging price fixing and supply reduction in the egg industry spanning more than a decade brought by a class of direct purchasers and other major corporations.
• Represented Norfolk Southern in the Surface Transportation Board proceeding reviewing Canadian Pacific Railway’s approx. US$31 billion acquisition of Kansas City Southern. 
• Represented Providence Equity Partners in a private nationwide antitrust class action filed in the U.S. District Court for the District of Massachusetts asserting broad-ranging antitrust conspiracy claims against Providence and other private equity firms regarding multi-billion dollar leveraged buyouts dating back to 2003. While other defendants paid multi-million dollar settlements to resolve the case, Carrie secured the dismissal of all claims against Providence at summary judgment.
• Represented MovieTickets.com as lead counsel in a number of consequential engagements, including:
  
  • winning the dismissal of all claims in a purported consumer class action filed against MovieTickets and Webloyalty.com, Inc. in the U.S. District Court for the Southern District of California and before the Ninth Circuit. Carrie successfully negotiated a favorable settlement resolving a preceding investigation by the New York Attorney General.
  • advising in connection with its sale to Fandango, in a deal that joined together two major online movie-ticketing services. Carrie navigated the company through a civil investigative demand from the DOJ, liaised with the Antitrust Division, and ultimately successfully secured unconditional clearance of the deal.
• Represented confidential clients in responding to grand jury subpoenas from the Department of Justice and successfully negotiating resolution of criminal allegations with no further action or publicity.
• Represented a global hospitality company in a confidential investigation by the FTC and other major hotel companies in the United States in connection with allegations that the hotels illegally conspired to suppress competition for online advertising via agreements to fix bidding for key words in online search engines. Carrie was able to resolve the investigation with very limited discovery and no public announcements or undertakings.
• Represented a global hospitality company  in devising comprehensive antitrust compliance policies reflecting legal parameters and strategic objectives across jurisdictions, including analysis of pricing and distribution/franchise programs and policies and design and implementation of global training programs to ensure a culture of compliance throughout the organization.
• Represented a group of insurance carriers in one of the largest antitrust MDLs in the country, where several purported classes of subscriber and provider plaintiffs allege various Blue Cross/Blue Shield entities and their Association illegally allocated markets and fixed prices in violation of state and federal antitrust laws.
• Represented The Great Atlantic & Pacific Tea Company, Inc. (A&P) in connection with antitrust issues at the core of its chapter 11 restructuring. As part of the chapter 11 plan, A&P sought to sell all of its 300+ stores. Through persuasive advocacy to the FTC and effective use of the rarely successful failing firm defense, Carrie obtained clearance from the FTC for the sale of 120 stores to supermarket competitors and stalking-horse bidders.

Some of the above matters were handled prior to joining Sidley.