image description

Diane L. McGimsey


Diane L. McGimsey

Los Angeles +1-310-712-6600+1-310-712-6600 +1-310-712-8800+1-310-712-8800
[email protected]

Diane McGimsey is a member of the Firm’s Litigation Group. Before joining S&C, she served as a law clerk to Justice Clarence Thomas of the U.S. Supreme Court and to Chief Judge J. Harvie Wilkinson III of the U.S. Court of Appeals for the Fourth Circuit.

Ms. McGimsey has represented clients in a wide range of federal and state litigation matters at both the trial and appellate level, with a particular focus on shareholder litigation and the defense of private class action securities and antitrust litigation. 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.


  • “Employers’ Guide to Return-to-Work Considerations During the COVID-19 Outbreak,” Reuters Westlaw (co-author) (April 2020)
  • “Expert Q&A on Seeking or Opposing Certiorari in the US Supreme Court,” Practical Law Litigation (co-author) (February/March 2018)
  • “Expert Q&A on Best Practices for Amicus Briefing,” Practical Law Litigation (author) (August/September 2016)

Community Service

  • Member of Board, Western Justice Center
  • Member of Board, Salvatori Center for the Study of Individual Freedom


Securities and Complex Commercial Litigation
  • Volkswagen AG, in its landmark $14.7 billion settlement that solves civil claims related to 475,000 2.0-liter diesel engine vehicles in the United States. The resolution was achieved with multiple government agencies, 44 U.S. states and private plaintiffs. Also advised Volkswagen on its 3-liter class action and regulatory settlements.
  • Real estate investor Richard D. Cohen in obtaining a favorable ruling in a federal bench trial in the Southern District of New York over Mr. Cohen’s personal liability for a loan obtained by entities he controlled to buy a San Francisco residential apartment complex known as Rincon Center.
  • BP p.l.c. in securities class action litigation arising out of the August 2006 shutdown of the facilities in Prudhoe Bay, Alaska, including in a successful interlocutory appeal to the Ninth Circuit
  • JPMorgan Chase and its affiliates in connection with litigation related to residential mortgage backed securities
  • TCL Chinese Theatres, in litigation over permitted uses of the Dolby Theatre in Los Angeles, a live-performance auditorium used to host the Academy Awards
  • Standard Chartered Bank in investor arbitrations and litigations relating to investments to feeder funds to Bernard L. Madoff Securities
  • RBC Capital Markets and other underwriters in a class-action litigation relating to the U.S. Auto Parts Network, Inc. IPO
  • Thomas Weisel Partners in FINRA disciplinary proceeding alleging fraud in connection with the sale of auction rate securities
  • The former CEO of International Rectifier in class action and derivative litigation, SEC and criminal investigations relating to a restatement, and trade secret and wrongful termination litigation
  • UBS Securities in class action and derivative litigation relating to the sale of Hollywood Entertainment to Movie Gallery
  • General Growth Properties (“GGP”) in an appeal of an adverse $95 million judgment in an action by a rival mall developer on a claim of tortious interference (another firm represented GGP during the underlying trial)

M&A-Related Litigation

  • CEO and Chairman of Activision-Blizzard in litigation over a transaction involving the restructuring of Vivendi’s ownership
  • Amylin in expedited litigation in Delaware Chancery Court, and later in an appeal to the Delaware Supreme Court, relating to a proxy contest
  • Hilton Hotels in litigation relating to its acquisition by Blackstone
  • Mitsubishi UFJ Financial Group in litigation relating to its acquisition of UnionBanCal Corporation
  • Swift Transportation in litigation relating to a going private transaction

Antitrust Litigation

  • BP West Coast Products in a class action involving alleged manipulation of retail gas prices
  • Cablevision Systems Corporation in a class action challenging the bundling of cable programming
  • EnCana Corporation in multiple antitrust actions involving alleged manipulation of natural gas prices
Governmental, Regulatory and Other Investigations
  • FinTech company in conducting an internal investigation and responding to high-profile allegations of a toxic environment due to sexual harassment and misconduct
  • Former CEO of Fortune 500 semiconductor company in DOJ and SEC investigations relating to alleged accounting irregularities
  • Thomas Weisel Partners in FINRA investigation and disciplinary proceedings relating to transactions involving auction rate securities


  • AmLaw Litigation Daily – Runner Up, “Litigator of the Week” (January 2022)
  • Benchmark Litigation – Labor & Employment Star (2021, 2022, 2023)
  • ​Daily Journal – Top Women Lawyers (2016, 2017, 2018)
  • Law360 – Rising Star in Banking (2015)
  • Los Angeles Business Journal – recognized as one of the “Women Making a Difference” in Los Angeles (2014, 2015)