From 1990 until 1992, Tigar served as a litigation associate for the law firm Morrison & Foerster. He then served as a public defender in San Francisco from 1993 until 1994. Tigar practiced complex commercial litigation, and became a partner, at the law firm Keker & Van Nest from 1994 until 2002. From 2002 to 2013, Tigar served as a judge on the Alameda County Superior Court.[2]
Tigar is an elected member of the American Law Institute, for which he served as an adviser to the Restatement (Third) of Torts: Liability for Economic Loss and now serves in the same capacity on the forthcoming Restatement (Third) of Torts: Defamation and Privacy.[3][5] Tigar has taught Pretrial Litigation at UC Berkeley School of Law. He previously served as a member of the California Judicial Council's Advisory Committee on Civil Jury Instructions and the Ninth Circuit's Jury Instructions Committee. From 2016 to 2019, he was the Judicial Representative to the Section of Antitrust Law of the American Bar Association. He is a Fellow of the American Bar Foundation.
On April 2, 2015, Tigar ordered the California Department of Corrections ("CDCR") to provide gender reassignment surgery to a transgender inmate, finding that such surgery was the only adequate medical treatment for the inmate's gender dysphoria.[6]
Since August 2017, Tigar has presided over Plata v. Newsom, a case concerning the constitutional adequacy of medical care in the California state prison system. On September 27, 2021, Tigar ordered that all CDCR staff, including medical and custody staff, be vaccinated against COVID-19, subject to medical and religious exemption.[7] Tigar found that because the undisputed evidence showed that staff were the means for COVID to enter the prisons, allowing prison employees to remain unvaccinated violated incarcerated persons' Eighth Amendment constitutional rights. On April 25, 2022, the Ninth Circuit vacated Tigar's order, finding that CDCR's refusal to require its custody staff to accept the vaccine did not constitute deliberate indifference.[8]
On November 19, 2018, Tigar issued a nationwide injunction barring the Trump administration from enforcing a rule that would deny asylum to anyone who entered the United States somewhere other than at a designated port of entry.[9] Complaining about the ruling, President Trump characterized Tigar as an "Obama judge"—prompting Chief Justice John Roberts to respond, "We do not have Obama judges or Trump judges, Bush judges or Clinton judges. What we have is an extraordinary group of dedicated judges doing their level best to do equal right to those appearing before them. That independent judiciary is something we should all be thankful for."[10] The Ninth Circuit Court of Appeals upheld Tigar's injunction,[11][12] and the Supreme Court allowed it to remain in place pending appeal.[13] On February 2, 2021, President Biden signed Executive Order 14010 revoking Proclamation 9880 of May 9, 2019 (Addressing Mass Migration Through the Southern Border of the United States),[14] thereby abrogating the rule limiting asylum claims.
On July 24, 2019, Tigar issued a nationwide injunction that barred the Trump administration from denying asylum to persons who crossed through but did not apply for asylum in a third country.[15] In August, the Court of Appeals for the Ninth Circuit found the administration's asylum policy "likely violated federal regulatory law" but narrowed Tigar's injunction to apply only within the Ninth Circuit.[16] On September 9, 2019, Tigar reinstated the nationwide scope of the injunction.[17] The Supreme Court stayed both orders on September 11, 2019, without addressing the legality of the administration's asylum policy.[18] On July 6, 2020, the Ninth Circuit affirmed the injunction blocking the third country asylum bar and upheld the nationwide scope of the injunction.
In November 2020, Tigar issued an order enjoining the California Department of Motor Vehicles from enforcing a ban on personalized license plate configurations it found “offensive to good taste and decency” on the grounds that the regulation violated the First Amendment to the United States Constitution.[19] Tigar wrote that the DMV's “good taste and decency” standard created “a facial distinction between societally favored and disfavored ideas” and that “the public expression of ideas may not be prohibited merely because the ideas are themselves offensive to some of their hearers.”[20]