A divided panel of the Fifth U.S. Circuit Court of Appeals ruled 2–1 on 4 July that Texas may not enforce Senate Bill 4, a 2023 statute empowering state and local police to arrest and prosecute people suspected of crossing the U.S.–Mexico border illegally. The decision keeps in place a lower-court injunction that has blocked the measure since February 2024. Writing for the majority, Judge Priscilla Richman, joined by Judge Irma Carrillo Ramirez, said SB 4 intrudes on the federal government’s exclusive authority over immigration, citing nearly 150 years of Supreme Court precedent. Judge Andrew Oldham dissented, arguing the ruling strips Texas of its sovereign right to police the border. SB 4 makes illegal entry or re-entry a state crime and allows state judges to order offenders removed from the United States, with prison sentences of up to 20 years for those who refuse to comply. Governor Greg Abbott signed the law in December 2023, calling it necessary because federal enforcement was inadequate. Thursday’s opinion affirms U.S. District Judge David Ezra’s preliminary injunction. The Supreme Court briefly allowed SB 4 to take effect in March, but the Fifth Circuit halted enforcement hours later pending review. Texas Attorney General Ken Paxton said he will seek further appeal. Immigrant-rights organisations, including the Las Americas Immigrant Advocacy Center and the American Civil Liberties Union, which brought the suit after the Biden administration initiated and the Trump administration later withdrew federal opposition, welcomed the decision as a reaffirmation of federal primacy in immigration policy.