A federal judge in California has barred Border Patrol agents from arresting someone suspected of living in the U.S. illegally unless they have a warrant or a reason to believe the person might flee before a warrant can be obtained.

U.S. Customs and Border Protection says the United States Border Patrol has arrested more than three dozen people who were in Maine illegally.

Border Patrol agents carried out sweeps in California’s Central Valley. Lawyers argued that people were stopped and arrested based on their skin color.