Ethan Dettmer is a partner in Gibson, Dunn & Crutcher’s San Francisco office where he is a member of the firm’s Litigation practice, and serves on the steering committee of the firm’s Securities Litigation Practice Group.

Mr. Dettmer is a trial lawyer who has represented clients in a wide variety of business-related disputes, including privacy and technology, securities, insurance, corporate governance, professional malpractice, and transnational litigation. He has represented clients in high-profile constitutional litigation involving equal protection and due process claims, and cases involving First Amendment and preemption questions. He also represents clients in connection with governmental investigations and internal corporate investigations.

Representative Matters:​​

• Mr. Dettmer led the Gibson Dunn team that sued on behalf of six individual DACA recipients in related cases that won the first nationwide injunction preventing the rescission of DACA.  Regents v. Dept. of Homeland Security, 279 F.Supp.3d 1011 and  298 F.Supp.3d 1304 (N.D. Cal.), aff’d, 908 F.3d 476 (9th Cir. 2018).  Mr. Dettmer was also one of the leaders of the team that successfully defended DACA in the Supreme Court, winning a significant victory on behalf of DACA holders and their families.  Dep’t of Homeland Security v. Regents, 140 S. Ct. 1891 (2020).  The Daily Journal named Mr. Dettmer among its 2018 California Lawyers of the Year for his work in this case.
• Representing Facebook in novel, intense, and wide-ranging investigations regarding data privacy risk, as well as related litigation against app developers.
• Won an important ruling on behalf of Daniel Ramirez, a DACA holder who was arrested and had his DACA stripped away based on the government’s false accusation that he was a gang member. The Court entered a preliminary injunction requiring the government to maintain Mr. Ramirez’s DACA status, and prohibiting any further claims by the government that he is a gang member or a threat to public safety.  Ramirez-Medina v. U.S. Dept. of Homeland Security, F. Supp.3d , 2018 WL 2214085 (W.D. Wash. May 15, 2018).
• Represented Aetna in a four-week jury trial in California state court in 2016. The jury awarded Aetna $37.4 million against a group of 10 defendants, individuals and surgery centers, who had conspired to create and run a sophisticated insurance fraud scheme.  The jury found in Aetna’s favor on all causes of action and awarded the full amount of damages requested.  The case was one of the top plaintiffs’ verdicts by impact in 2016.
• Successfully represented the University of California in a seven week bench and jury trial in California state court against an international consulting firm in a case alleging claims for professional malpractice, breach of contract, and under the False Claims Act.
• Member of the trial team in a RICO suit against conspirators seeking to extort billions of dollars from Chevron Corporation based on fraudulent environmental claims and a sham Ecuadorian lawsuit. Chevron Corp. v. Donziger, 974 F. Supp. 2d 362 (S.D.N.Y. 2014), aff’d 833 F.3d 74 (2d Cir. 2016), cert. den. 137 S.Ct. 2268 (2017).  He is also a member of the team representing Chevron against that conspiracy in related litigation in multiple venues.
• Convinced the California Court of Appeal to affirm the dismissal of a challenge to the disciplinary process and disclosure system of the Financial Industry Regulatory Authority (“FINRA”) on federal preemption and related grounds. Flowers v. FINRA, 16 Cal. App. 5th 946 (2017).
• Prevailed in California state court trials on FINRA’s behalf in cases challenging its broker disclosure system, and successfully defended FINRA in a case challenging FINRA’s member disciplinary system. Charles Schwab & Co., Inc. v. FINRA, 861 F. Supp. 2d 1063 (N.D. Cal. 2012).
• Member of the trial team that successfully challenged California’s Proposition 8 in federal court under the United States Constitution, vindicating marriage equality in California. Perry v. Schwarzenegger, 704 F. Supp. 2d 921 (N.D. Cal. 2010), aff’d sub nom. Perry v. Brown, 671 F.3d 1052 (9th Cir. 2012), vacated and remanded, 133 S.Ct. 2652 (2013).  Dettmer represented 65 current and former California legislators as amici curiae  in the California Supreme Court in the earlier challenge to Proposition 8 under the California Constitution. Strauss v. Horton, 46 Cal.4th 364 (2009).
• Convinced the Ninth Circuit to affirm the immunity of two arbitrators who had been sued by a party’s representative in an arbitration. Sacks v. Dietrich, 663 F.3d 1065 (9th Cir. 2011).
• Member of the team that won summary judgment on behalf of The Williams Companies, Inc. and its former CEO in securities litigation seeking nearly $3 billion in damages in connection with the bankruptcy of Williams’ former telecommunications subsidiary. He was also one of the Gibson Dunn lawyers who subsequently defended that summary judgment victory on appeal.  In re Williams Companies Securities Litigation, 558 F.3d 1130 (10th Cir. 2009); see 558 F.3d 1144 (10th Cir. 2009) (upholding, in the same case, what plaintiffs labeled “the highest costs award in the history of American jurisprudence” in favor of Williams and the other defendants).

Mr. Dettmer was one of the founding co-chairs of the Bay Area Offices’ Pro Bono Committee, and has argued appeals and led successful trial teams on behalf of pro bono clients in state and federal courts.  He serves as a member of the board of directors of OneJustice, which is dedicated to expanding the availability of legal aid to Californians in need (www.one-justice.org).  He is also a member of the pro bono advisory board of Swords to Plowshares, which serves homeless veterans in the Bay Area (www.swords-to-plowshares.org).

Mr. Dettmer is the chair of Gibson Dunn’s firm-wide Associates Committee, and serves as the hiring partner for the firm’s San Francisco office.  He is also a member of the firm’s Associate Compensation, Hiring, and Professional Development Committees.  He is co-author of the firm’s treatise entitled “Securities Litigation:  A Practitioner’s Guide” (published by PLI).

Mr. Dettmer is a member of the State Bars of California and Michigan, and is admitted to practice in various federal courts.  He was a law clerk to the late Justice James H. Brickley of the Michigan Supreme Court before joining Gibson Dunn, and is an honors graduate of Harvard College and the University of Michigan Law School.  Mr. Dettmer was an admissions and financial aid officer at Harvard and Radcliffe Colleges before attending law school.