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Practice Areas
Education & Honors
  • Yale Law School, J.D., 1979; Note Editor, Yale Law Journal
  • Brown University, A.B., magna cum laude, 1975; Phi Beta Kappa
  • "AV-Rated" by Martindale-Hubbell®
Bar & Court Admissions
  • District of Columbia and New York
  • United States Courts of Appeals for the Second, Eighth, Ninth, District of Columbia, and Federal Circuits
  • United States District Courts for the Southern District of New York and District of Columbia
  Gerson A. Zweifach
Of Counsel
TEL: 202-434-5534
FAX: 202-434-5029
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Williams & Connolly LLP
725 Twelfth Street, N.W.
Washington, D.C. 20005


Gerson Zweifach has tried antitrust, securities, libel, and complex commercial cases to juries and courts across the United States.  Over 29 years at Williams & Connolly LLP, Mr. Zweifach's litigation practice has extended across a wide variety of substantive areas, as both plaintiff’s and defendant’s counsel, with a constant focus on trial work.  He has also served as lead counsel in challenges to two of the leading biotechnology patents.

In the securities field, Mr. Zweifach has represented both plaintiffs and defendants in a wide variety of actions, including the successful defense at a jury trial of an issuer sued for allegedly imposing unauthorized trading restrictions on the company's shares. Mr. Zweifach has also been called upon to defend major law firms in securities and malpractice litigation and before the Securities and Exchange Commission.

In the antitrust field, Mr. Zweifach has successfully defended monopolization, tying, and patent antitrust actions brought in federal courts across the country.

Mr. Zweifach’s recent matters have included the representation of Richard A. Grasso in Spitzer v. Grasso in the New York state courts, as well as the representation of Medimmune in its challenges to Genentech’s Cabilly patent in federal court in Los Angeles and PDL’s Queen patent in federal court in San Jose.  He is listed in the Best Lawyers in America (2005-08); Chambers USA Guide (2005-08); Lawdragon 500 (2007-10); and The Legal 500 – United States (2009).