Mark Tomaier is an associate in the Orange County office of Gibson, Dunn & Crutcher where he currently practices in the firm’s Litigation Department and is a member of the Environmental Litigation and Mass Tort Practice Group. He represents clients in complex litigation, government investigations, and compliance matters primarily relating to environmental law. He was named by the Environmental Law Institute as a 2022 “Emerging Leader” in environmental law and policy.

His substantive experience includes:

• Representing aerospace company in matter involving alleged trichloroethylene (“TCE”) contamination.
• Representing chemical manufacturing and retail clients in government investigations focused on environmental tort and compliance issues.
• Providing compliance and enforcement counseling addressing Clean Air Act, Clean Water Act, and CEQA in oil and gas operations.
• Providing environmental due diligence in complex transactions.
• Successfully arguing before the Ninth Circuit to obtain reversal of a Board of Immigration Appeals decision that had ordered removal of a United States permanent resident who had been deemed not mentally competent to represent himself.

Mark serves as a co-chair of the firm’s Sustainability Committee and on the Executive Committee of the Environmental Law Section of the Los Angeles County Bar Association. Prior to joining the firm, Mark served as a law clerk to The Honorable Marilyn L. Huff in the United States District Court for the Southern District of California and as a law clerk to The Honorable Michael D. Wilson in the Supreme Court of Hawaii.

Mark earned his law degree cum laude  in 2017 from Harvard Law School, where he was an Articles Editor on the Harvard Environmental Law Review. In 2012, he graduated with highest honors from the University of California Berkeley with a Bachelor of Arts Degree, double majoring in English and in Rhetoric. Mark holds a 2022 Certificate in Sustainable Capitalism and ESG from the University of California, Berkeley.

He is a member of the California Bar. Mark is admitted to practice before the United States Court of Appeals for the Ninth Circuit and before the United States District Court for the Central District of California.