A group immigrants and legal advocates filed a class-action lawsuit Wednesday that seeks to stop Immigration and Customs Enforcement officers from arresting migrants who appear at immigration courts for previously scheduled hearings and placing them on a fast-track to deportation.

Civil rights groups sued the Trump administration on Wednesday in a bid to stop the government’s policy of allowing Immigration and Customs Enforcement officers to arrest undocumented migrants who show up for immigration hearings at courthouses.

Immigration advocates have feared the Trump administration’s mass detentions will prompt people to abandon their asylum claims. On Tuesday, one person did.