The underlying fight is about whether California can require federal immigration and law enforcement agents to visibly display their agency name and a name or badge number while conducting arrests, detentions, or crowd-control operations on California soil. California enacted the requirement — Section 10 of the No Vigilantes Act, codified at California Penal Code § 13654 — on September 20, 2025, in response to what the legislature described as the United States's broad immigration enforcement efforts. Officers who willfully and knowingly violate the law face misdemeanor prosecution under state law.
The Ninth Circuit, in an opinion by Judge Mark J. Bennett, with Judges Jacqueline H. Nguyen and Daniel P. Collins also on the panel, held that Section 10 attempts to directly regulate the United States in its performance of governmental functions, which the Supremacy Clause forbids. The panel held that the intergovernmental immunity doctrine bars states from regulating the federal government qua government — controlling federal governmental functions in any manner and to any degree — and that no de minimis exception exists.
The panel rejected the district court's framing of the question. Judge Christina A. Snyder had denied a preliminary injunction after concluding that the United States had not shown that its current practices with respect to identification are essential to federal law enforcement operations such that state regulations in those areas seek to interfere with or control federal law enforcement functions. The Ninth Circuit held that was the wrong standard — one applicable to state regulation of federal contractors and third-party employers, not to direct regulation of the government itself. Because Section 10 expressly applies to federal officers and purports to override the federal government's power to determine whether, how, and when to publicly identify its agents, it directly regulates inherently governmental conduct.
The panel also rejected California's argument that the court should separately weigh the public safety concerns that prompted the Act. Because the United States demonstrated a likelihood of success on the Supremacy Clause claim, the panel held that irreparable harm, a favorable balance of equities, and the public interest all follow as a matter of course, and that no further balancing was required.
The injunction covers Section 10 only. The United States also challenged Section 2 of the No Vigilantes Act, which directs agencies to adopt and publicly post written identification policies, but did not contest the district court's ruling that it lacked Article III standing to challenge that provision. A separate challenge to the No Secret Police Act — which prohibits law enforcement officers from wearing facial coverings during the performance of their duties — is not before the panel on this motion.
The case is United States of America v. State of California, et al., No. 26-926, in the United States Court of Appeals for the Ninth Circuit, on appeal from the Central District of California, D.C. No. 2:25-cv-10999-CAS-AJR. The defendants include the State of California, Governor Gavin Newsom, and Attorney General Rob Bonta, each named in their official capacities.