US immigration agents in Oregon must stop arresting people without warrants unless there is a likelihood of escape, a federal judge ruled on Wednesday.

US district judge Mustafa Kasubhai issued a preliminary injunction in a proposed class-action lawsuit targeting the Department of Homeland Security’s practice of arresting immigrants they happen to come across while conducting ramped-up enforcement operations – which critics have described as “arrest first, justify later”.

Similar actions, including immigration agents entering private property without a warrant issued by a court, have drawn concern from civil rights groups across the country amid Donald Trump’s mass deportation efforts.

Courts in Colorado and Washington DC, have issued rulings like Kasubhai’s, and the government has appealed them.