William H. Stallings is an Antitrust & Competition partner in Mayer Brown's Washington DC office. Previously, he spent 17 years at the US Department of Justice’s (DOJ) Antitrust Division, culminating with his service as the Chief of the Transportation, Energy, and Agriculture Section. Bill advises clients on a full range of competition and consumer protection issues, including DOJ/FTC merger compliance and litigation; private antitrust litigation, including class actions; and global and US government competition and consumer protection investigations. For his outstanding service in antitrust enforcement, the DOJ awarded Bill the prestigious Neil E. Roberts Award (2015). In 2016, the National Law Journal recognized Bill as an Antitrust Trailblazer.

Since joining Mayer Brown in 2015, Bill has handled several high-profile client matters, including serving as lead antitrust counsel in a multibillion-dollar merger that closed successfully following a DOJ second request investigation and private litigation. Bill is also active in the following capacities:

  • Non-Governmental Advisor (on behalf of the US DOJ) to the International Competition Network (ICN), an international organization of more than 100 competition agencies with the common aim of addressing practical antitrust enforcement and policy issues.
  • Co-chair of the new Antitrust, Competition and Consumer Protection Committee of the American Bar Association’s (ABA) Air & Space Forum.
  • Vice-chair of the Transportation and Energy Industries Committee of the ABA's Antitrust Section.

Bill is a co-leader of Mayer Brown's Aviation industry group and assists clients (including airlines, airports, executives, handlers and investors) in navigating complex competition issues in the aviation sector. He is familiar with the approaches of the most active competition authorities on the assessment of mergers, alliances and code-sharing agreements in this sector.

As chief of the Transportation, Energy, and Agriculture Section at the DOJ, Bill was responsible for civil antitrust enforcement, competition advocacy and competition policy in areas such as domestic and international aviation, electricity, oilfield services and agricultural commodities. He supervised the section's investigations of antitrust violations, managed dozens of second-request merger matters, shaped substantive analyses, engaged with international antitrust authorities, presented matters to DOJ leadership and litigated enforcement actions. Bill was appointed assistant chief of the section in 2005 and chief in 2011.

Learn more about the high-profile and precedent-setting matters Bill handled during his DOJ career.


At Mayer Brown

  • Lead antitrust counsel to Virgin America in its multibillion-dollar acquisition by Alaska Airlines in 2016, creating the fifth-largest airline in the United States. Bill advised Virgin America on the antitrust considerations relating to the sale, represented the company before the US Department of Justice’s (DOJ) Antitrust Division throughout the department’s in-depth review and handled private litigation that threatened to derail the transaction.
  • Represented Foster Farms in connection with an Federal Trade Commission (FTC) investigation of whether certain statements on product labels were unfair or deceptive. After an extensive investigation, including Mayer Brown white papers and other submissions, the FTC issued a public closing letter in which it declined to take action.
  • Advised numerous domestic and global companies on the antitrust implications of potential transactions under consideration.
  • Represented companies in federal court and before the DOJ and FTC in merger and competition-related proceedings.

While at DOJ

  • Developed the legal precedent in the KeySpan and Morgan Stanley cases for holding financial institutions liable for Sherman Act violations arising from the use of derivative agreements.
  • Obtained, for the first time, disgorgement of ill-gotten gains as a remedy for Sherman Act (KeySpan) and Clayton Act (New York Tour Buses) violations.
  • Led the Antitrust Division’s investigation of US Airways’ acquisition of American Airlines, which resulted in the divestiture of an unprecedented number of slots and gates at some of the most important US airports.
  • Directed the Antitrust Division’s investigation of the merger of National Cinemedia and Screenvision, the two top US cinema advertising networks. The parties abandoned the transaction shortly before trial.
  • Managed the Antitrust Division’s successful challenge of the JBS/National Beef merger.
  • Served as a key member of the successful trial, appellate and judgment compliance teams in United States v. Visa.


University of North Carolina at Chapel Hill, BA

University of North Carolina School of Law, JD


  • District of Columbia