The move is likely to cause more court battles for an administration that has already faced numerous challenges to its immigration policies, notably its travel ban on people from Muslim-majority countries. The U.S. Immigration and Nationality Act allows people to apply for asylum even if they do not arrive at a designated point of entry.

The new interim federal rule says that people crossing the southern border “illegally” would be ineligible for asylum, and people should therefore be channelled to ports of entry “where they would be processed in a controlled, orderly and lawful manner.”

Ahead of the midterms, Trump talked repeatedly about a “caravan” of migrants who have been travelling through Central America toward the U.S. border. He suggested that this group constituted an invasion, and deployed thousands of active-duty troops to the border in anticipation.

Many of those in the convoy are fleeing violence in their home countries, and are likely to claim asylum. The new rule would force them to prove “reasonable fear” of returning, a higher standard than the “credible fear” test that currently applies.

Administration officials believe Trump has legal discretion to choose who gets into the U.S. and who doesn’t. “Consistent with our immigration laws, the President has the broad authority to suspend or restrict the entry of aliens into the United States if he determines it to be in the national interest to do so,” Homeland Security Secretary Kirstjen Nielsen and Acting Attorney General Matt Whitaker said in a joint statement.

Civil liberties activist, however, disagree. “The proposal is patently unlawful and there will be a court challenge,” said the ACLU’s Lee Gelernt, who is the deputy director of the group’s Immigrants’ Rights Project.