Sean P. Hennessy

Sean P. Hennessy

Senior Associate

Sean Hennessy focuses his practice on white collar criminal defense and complex commercial litigation. Mr. Hennessy recently rejoined the firm after serving as a law clerk for the Honorable John D. Bates of the United States District Court for the District of Columbia.

Mr. Hennessy's white collar defense experience includes counseling companies and individual executives in investigations concerning criminal antitrust matters, global anticorruption, and pharmaceutical marketing.

Mr. Hennessy's commercial litigation experience includes representing clients in False Claims Act, product liability, and consumer fraud litigation. He has experience with all aspects of litigation in federal and state courts including early case assessment, drafting dispositive motions, discovery, taking and defending depositions, expert discovery, and preparing for trial and appellate arguments.

Mr. Hennessy maintains an active pro bono practice, primarily representing criminal defendants in DC Superior Court, where he recently obtained a jury verdict acquitting his client on all charges in an aggravated assault trial.

Mr. Hennessy graduated from Georgetown University Law Center, where he was Executive Editor of the Georgetown Journal of International Law, participated in the Appellate Litigation Clinic, and was a member of the moot court team. Upon graduation, Mr. Hennessy was elected to the Order of the Coif and won the International Academy of Trial Lawyers Appellate Litigation Award. Prior to law school, Mr. Hennessy was a management consultant specializing in economic and financial analysis.


  • Former corporate executive in FCPA investigation by DOJ and SEC.
  • Sales executive of pharmaceutical manufacturer as counsel in criminal antitrust investigation by DOJ.
  • Pharmaceutical manufacturer as counsel in internal investigation focused on sales representative promotional activities.
  • Bristol-Myers Squibb and Sanofias counsel in Plavix product liability and False Claims Act litigation.
  • Government contractor in False Claims Act litigation.
  • Real estate investment trust in litigation assessment to determine whether to bring claims against hotel operator.


  • JD, Georgetown University Law Center, 2012, magna cum laude, Order of the Coif
  • MA, Economics, Fordham University, 2001
  • BA, Economics, Loyola University Maryland, 2000, magna cum laude
  • District of Columbia
  • Maryland
  • US District Court, District of Maryland
  • US District Court, District of Columbia, The Honorable John D. Bates

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