Diane McGimsey


Sullivan & Cromwell

Diane McGimsey is a litigation partner in Sullivan & Cromwell’s Los Angeles office and is a co-head of the Firm’s Labor and Employment Group. A former U.S. Supreme Court clerk to Justice Clarence Thomas, Diane represents clients in a wide range of federal and state litigation matters at both the trial and appellate level, with a particular focus on employment litigation, the defense of private class action securities and antitrust litigation, shareholder litigation and internal investigations. Her practice also includes investigations by the Department of Justice and the Securities and Exchange Commission, as well as handling matters for clients as plaintiffs in significant commercial disputes.

Regularly recognized by a number of leading legal publications, Diane has been recognized by the Los Angeles Business Journal’s “Leaders of Influence: Thriving in Their 40s” and “Women Making a Difference”; named to the Daily Journal’s “Top Women Lawyers,” a list of the most powerful lawyers in California; and listed as a “Labor and Employment Star” by Benchmark Litigation and a “Rising Star” in Banking by Law360.

Diane frequently speaks on the understanding of key labor and employment and corporate governance issues, including best practices for conducting internal investigations and updates on the ever-changing landscape on whistleblower and arbitration issues. Diane also presents client webinars on employment issues, including diversity, equity and inclusion, and helps maintain S&C’s active Labor and Employment blog.

Committed to public service, Diane sits on the boards of several philanthropic and advocacy organizations, including The Western Justice Center and Claremont McKenna College’s Salvatori Center for the Study of Individual Freedom. She is also a member of the Resource Board for the National Association of Women Judges and served on the Advisory Council of the National Association for Court Management’s “Courts in the Era of #WeToo” Education Initiative.

Diane received her B.A. from Claremont McKenna College and her J.D. from UC Berkeley School of Law.