C.J. Mahoney is a partner at Williams & Connolly LLP. His practice focuses on representing clients in complex commercial disputes, particularly in international and domestic arbitration. He is also a member of the firm’s White Collar Practice Group and has represented individuals and entities in a number of high-profile criminal prosecutions and investigations.

In addition to his counsel work, C.J. serves as a Visiting Lecturer at Yale Law School where he teaches a course on international arbitration.

Prior to joining Williams & Connolly in 2008, C.J. clerked for Judge Alex Kozinski of the United States Court of Appeals for the Ninth Circuit and then for Associate Justice Anthony M. Kennedy of the Supreme Court of the United States.

A Kansas native, C.J. graduated magna cum laude with an A.B. in Government from Harvard College in 2000, where he was a member of Phi Beta Kappa. He earned his J.D. from Yale Law School in 2006, where he was Editor-in-Chief of the Yale Law Journal. Prior to attending law school, C.J. worked as a business analyst at McKinsey & Company in New York.

C.J. serves on the steering committee of Young Attorneys in Alternative Dispute Resolution (Y-ADR), a leading organization for arbitration practitioners under the age of 45, sponsored by the International Institute for Conflict Prevention and Resolution (CPR).  He also is a member of CPR’s arbitration committee, the International Bar Association, and the International Law Section of the District of Columbia Bar. He has spoken at a number of international arbitration conferences and has served as a faculty member for the Foundation for International Arbitration Advocacy (FIAA).  He has been designated as a Rising Star by Super Lawyers magazine.

Representative Experience

Though all cases vary and none is predictive, C.J.’s experience includes:

International Arbitrations

  • Second chair in a Paris-based ICC arbitration involving a merger dispute. The dispute involved issues of French and Brazilian law and resulted in a $130 million award in the client’s favor.
  • Representation of Asian electronics company in ICC intellectual property dispute.
  • Lead counsel for Canadian engineering firm in AAA construction dispute.
  • Representation of American law firm in Zurich-based ICC legal malpractice dispute with German company involving issues of German professional liability and Swiss arbitration law.
  • Representation of American biotech firm in ICDR arbitration over dispute with Swedish supplier.
  • Representation of foreign state in connection with treaty dispute.
  • Representation of Brazilian businessman in connection with private equity dispute.
  • Representation of private aviation company in AAA arbitration against aircraft manufacturer concerning product defects.

In addition to his arbitration practice, C.J. has represented clients in a variety of criminal and civil matters in state and federal courts in the United States involving, inter alia, allegations of securities fraud and false statements, the Foreign Corrupt Practices Act, and the Civil RICO statute. 

Criminal and Civil matters in U.S. Courts

  • Defense of individuals and companies in congressional and Department of Justice Public Integrity and Criminal Fraud Section investigations.
  • Defense of insurance company and executives in civil RICO trial in the Southern District of New York.  The mattered ended in a favorable settlement.
  • Defense of former technology company CEO in options “backdating”-related civil and criminal litigation.  The government dropped all charges and the civil litigation ended with a favorable settlement.
  • Successful representation of the defendant in a major Fourth Amendment case before the Supreme Court of the United States, Bailey v. United States, 133 S. Ct. 1031 (2013).



Selected to Washington, D.C. “Rising Stars” list, Super Lawyers, 2014-2016


Government Service

Law Clerk, Justice Anthony Kennedy; Supreme Court of the United States, 2007-2008

Law Clerk, Chief Judge Alex Kozinski; United States Court of Appeals for the Ninth Circuit, 2006-2007

Professional Experience

Clinical Visiting Lecturer, Yale Law School, since 2014

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