Michael Mongan is a nationally recognized appellate lawyer who served as the Solicitor General of California from 2019 to 2025 and previously worked in private practice in California and in all three branches of the federal government in Washington, DC. He focuses on advising clients on complex state and federal appeals as part of WilmerHale’s Appellate and Supreme Court Litigation Practice, with a particular emphasis on clients and controversies in the Western United States. Mr. Mongan also supports the firm’s Crisis Management and Strategic Response and State Attorneys General Practices. 

As Solicitor General, Mr. Mongan was the chief appellate lawyer for the government of the world’s fourth largest economy. Recent profiles describe him as a “unicorn” and “a highly skilled appellate practitioner”—the “ultimate team player” who “delivered for Californians time and again.”

Mr. Mongan has briefed and argued dozens of cases in federal and state appellate courts, including some of the most important appellate matters of the last decade. For example, he successfully argued in the US Supreme Court in defense of the Affordable Care Act, the Deferred Action for Childhood Arrivals program (DACA), and California’s voter-enacted statute restricting the in-state sale of certain meat products. He has argued seven cases in the California Supreme Court, including successfully defending Proposition 22, a ballot initiative classifying mobile app-based drivers as independent contractors; defeating a state constitutional challenge to Proposition 69, which expanded the State’s crime-solving DNA database; and preserving the Governor’s constitutional authority with respect to tribal gaming compacts. And he has argued numerous cases before the California Courts of Appeal and the Ninth Circuit, including two en banc matters.

Mr. Mongan’s past work spans questions of state and federal constitutional law, administrative and regulatory law, criminal law, environmental law, privacy and consumer protection, intellectual property, antitrust, securities, class actions, and other commercial issues. He has worked with clients facing complex legal challenges in the technology, healthcare, financial services, energy, and education sectors, among others.

And Mr. Mongan is uniquely positioned to counsel clients regarding the multidimensional legal, policy and communications challenges that can arise from their interactions with state governments and the federal government. He served for more than a decade at the California Department of Justice—the largest state department of justice in the country—as Solicitor General and in other senior roles. His duties included advising the Attorney General, the Governor’s Office, and other state officials and agencies on a wide range of matters. He also worked closely with the offices of other state attorneys general on cross-cutting legal and policy issues. Earlier in his career, Mr. Mongan served as the Deputy Counsel to the Vice President during the first two years of the Obama Administration, on the majority staff of the US Senate Finance Committee, and as a law clerk for Justice David H. Souter on the US Supreme Court and Judge Merrick Garland on the DC Circuit. 

A native of the San Francisco Bay Area, Mr. Mongan attended Stanford University and Stanford Law School, where he graduated with honors and served as an editor of the Stanford Law Review and the Stanford Law & Policy Review.