The Trump administration on Wednesday unveiled a rule that allows officials to detain migrant families indefinitely while judges consider whether to grant them asylum in the United States, eliminating a previous 20-day limit.

The rule, which is certain to draw a legal challenge, would replace a 1997 court settlement that limits the amount of time U.S. immigration authorities can detain migrant children. That agreement is generally interpreted as meaning families must be released within 20 days.

It was the administration's third major regulation restricting immigration in little more than a month, all during an unsettled period when senior immigration officials hold "acting" titles lacking U.S. Senate confirmation.