John O’Toole focuses his practice on antitrust and competition matters. Mr. O’Toole has experience representing clients in a wide range of antitrust and competition matters, including criminal investigations, civil litigation, counseling, and merger review. Mr. O’Toole has particular experience at the intersection of antitrust and labor markets, representing numerous clients in civil and criminal investigations and civil litigation involving no poach, wage-fixing, and information exchange allegations.  Mr. O’Toole has represented clients across multiple fields, with experience in banking, technology, telecommunications, beverage and pharmaceutical industries.  Mr. O’Toole also maintains an active pro bono practice focused on LGBTQIA+-related advocacy.

Prior to joining the firm, Mr. O’Toole was an antitrust and competition associate at another multinational law firm in Washington DC. During law school, Mr. O’Toole served as an intern for the US Securities and Exchange Commission Division of Enforcement.

Professional Memberships

Mr. O’Toole is a Vice Chair for the American Bar Association Antitrust Section’s Legislation Committee. He is also a member of the National LGBT Bar Association.


  • Experience

    • Represents a financial services corporation in a suit brought by private plaintiffs challenging merger under Section 7 of the Clayton Act.
    • Represents global food corporation in a class action alleging anticompetitive information exchange among meat processors.
    • Represents large financial institution in challenges to its environmental, social, and governance (“ESG”) practices.
    • Represents ultra low-cost carrier airline in its application for antitrust immunity for a joint venture.
    • Successfully defended against summary judgment for generic pharmaceutical company challenging branded pharmaceutical’s contracting practices as a violation Section 2 of the Sherman Act.
    • Successfully closed criminal grand jury investigation into hiring practices without enforcement action.
    • Successfully represented a wireless telecommunications provider in $26 billion merger, including serving as a key member of trial team.
    • Represented a number of companies seeking leniency or otherwise being investigated for no-poach conduct.
    • Represented construction materials company in grand jury investigation alleging market allocation scheme, which was successfully closed without enforcement action.
    • Represented a generic pharmaceutical company in both civil litigation and criminal investigation alleging price-fixing for various molecules.
    • Represented individual defendant charged with involvement in alleged bid rigging conspiracy.


  • Selected for inclusion in Best Lawyers: Ones to Watch (2024).
  • Mr. O’Toole was nominated for a 2021 Concurrences Antitrust Writing Award. 

Insights & News


  • Education

    • JD, Harvard Law School, 2017

      Supervising Editor, Harvard Journal on Legislation

      Professional Liaison, Lambda Law

    • BA, Philosophy, Boston College, 2011

      summa cum laude

      Phi Beta Kappa

  • Admissions

    • District of Columbia