A federal judge in California on Tuesday issued a nationwide injunction barring the Trump administration from arresting migrants at immigration courthouses, ruling that the practice violated the Administrative Procedure Act. US District Judge Casey Pitts, an appointee of former President Joe Biden, found that the Department of Homeland Security and its immigration enforcement agencies had provided no reasoned explanation for reversing a decades-old policy against such arrests, describing the change as “arbitrary and capricious” and the result of “a complete lack of decision-making.” The order extends beyond a May ruling by a New York federal judge that had restricted courthouse arrests only within that state.

The Department of Homeland Security’s general counsel, James Percival, sharply criticised the ruling as “naked judicial activism in service of an anti-American, open borders agenda,” arguing that a noncitizen ordered removed by an immigration judge should be taken into custody just as a convicted criminal defendant is. The practice, which began shortly after President Donald Trump’s return to office, saw plainclothes Immigration and Customs Enforcement (ICE) agents detain individuals in courthouse hallways, often after prosecutors dismissed their cases. Judge Pitts also faulted the administration for holding detainees in nearby cells beyond a prescribed 12-hour limit, and noted that the arrests had a “chilling effect” on migrants’ willingness to attend hearings.

The courthouse ruling came on the same day the US Supreme Court’s conservative majority delivered a separate decision that strengthens the hand of border agents in removing lawful permanent residents, or green card holders. In a 6-3 vote, the justices held that border officials need only a “reason to believe” a returning green card holder has committed a crime involving moral turpitude to deny re-entry, rather than having to prove it by clear and convincing evidence. The ruling, written by Justice Clarence Thomas, drew a dissent from Justice Ketanji Brown Jackson, who warned it gave the government “a massive blank check.” Viewed from Washington, the two rulings illustrate the uneven judicial terrain the administration navigates as it tests the limits of executive power to accelerate deportations.

The nationwide injunction is the latest in a series of legal challenges to Trump’s immigration enforcement tactics, which have included expanded fast-track deportations, the use of third countries for removals, and the suspension of naturalisation ceremonies for nationals of certain states. The administration has argued that the United States faces an “invasion” by criminals and has sought broad authority to detain and remove undocumented migrants. The government is expected to appeal the courthouse arrest ban, while immigration attorneys and advocacy groups in California and New York have signalled they will continue to challenge enforcement methods they argue undermine due process. The case now moves to the appellate level, where the scope of agency discretion under the Administrative Procedure Act will be further tested.