Described in Chambers USA as a “real trial lawyer,” “a giant in the legal community,” and a “creative thinker and problem solver,” Brian Hennigan is consistently recognized as one of the nation’s leading litigators. Over the course of his career, he has focused on complex litigation, with an emphasis on white collar criminal defense and investigations. For the past three decades, Mr. Hennigan has successfully represented individuals and corporations facing a wide array of challenges presented by federal prosecutors and investigating agencies. In addition to his white collar practice, he has represented Fortune 500 corporations in a variety of civil disputes, including antitrust, class action, trade secret, and unfair competition litigation. Mr. Hennigan has conducted numerous, successful internal investigations for state and private universities, labor unions and other entities.
A founding partner of Hueston Hennigan, Mr. Hennigan is a fellow of the American College of Trial Lawyers, an invitation-only fellowship of “exceptional trial lawyers” who have “demonstrated the very highest standards of trial advocacy, ethical conduct, integrity, professionalism and collegiality.”
Mr. Hennigan has earned significant praise from clients and colleagues for his white collar practice. Chambers USA has ranked him every year since 2008 in the White Collar Crime & Government Investigations category. Benchmark Litigation has also recognized him as one of the “Top 20 Trial Lawyers in California” and the “Top 100 Trial Lawyers in America.”
Prior to entering private practice, Mr. Hennigan served as an assistant U.S. attorney in the Central District of California, where he was an assistant division chief for the office’s Criminal Division. In this position, he conducted numerous grand jury investigations, served as lead trial counsel in more than 30 trials, and successfully represented the U.S. in multiple appeals before the U.S. Court of Appeals for the Ninth Circuit. Mr. Hennigan received commendations for his work in the U.S. Attorney’s Office from the U.S. Department of Justice and numerous other government agencies.
Updated Nov 2025
Represented an executive in a criminal antitrust case related to the alleged bid-rigging on fuel oil prices by Korean fuel oil companies in sales to the U.S. military. Mr. Hennigan was retained in this matter after the indictment charging his client with antitrust and mail fraud felonies had been returned by the grand jury. Based on his thorough review of the underlying documents, as well as an analysis of the Korean government’s investigation of the same underlying facts, Mr. Hennigan and his team negotiated a resolution of the matter, with the dismissal of all felony charges, and the entry of a plea to misdemeanor charge, with a binding agreement for a non-custodial sentence. The matter resolved in September 2025.
Conducted an internal investigation on behalf of the Los Angeles County Federation of Labor on a high-profile matter which the client deemed “highly sensitive.” The underlying conduct related to the unauthorized recording of conversations between elected city officials and union officials. The subject matter of those conversations led to the resignation from office of the Los Angeles City Council president and the president of the Federation of Labor. At the conclusion of the internal investigation, the client expressed his enthusiastic support for the firm’s ability to conduct this highly sensitive investigation with speed and focus, praising the investigation strategy as being “creative and on point.“
Represented the University of California Board of Trustees in a high-profile internal investigation of the Office of the President related to alleged improper activity in response to a state audit. The result of this work led to corrective actions within the Office of the President. His work on this matter garnered a California Lawyer Attorney of the Year (CLAY) award.
- Represented Fat Brands in a federal criminal case charging the client and others with securities and tax fraud. The case was dismissed in August 2025.
- Commercial disputes
- Securities
- White collar crime
- Energy
- Financial services
- Government and public policy
- Healthcare
- Northwestern Pritzker School of Law (J.D.) cum laude
- Northwestern University (B.A. Economics)
- Fellow, American College of Trial Lawyers
- Board member, Executive Committee, Northwestern University Law School
- Former co-chair, Loyola Law School, Project for the Innocent
- Board member, Social Justice Legal Foundation
- Board member and former president, Federal Bar Association, Los Angeles chapter
- Member and former co-chair, American Bar Association, White Collar Crime Committee
- California
- Illinois