Immigration advocacy groups filed a legal challenge in federal court Thursday to halt a directive proposed by Attorney General William Barr that would force asylum-seekers to remain in immigration detention until their cases are decided.

Barr, who oversees the nation's immigration courts, issued a decision on April 16 ordering immigration judges to deny bond hearings for asylum seekers, which would keep migrants in detention while they wait months, even years, for their claims to be heard.

That represents a departure from the long-standing practice used under Republican and Democratic administrations of allowing asylum seekers to be released into the U.S. on bail if they show they have a credible fear of persecution in their home country and do not pose a threat to U.S. communities.

Recognizing that the new rule would have an "immediate and significant impact" on the Department of Homeland Security's ability to detain potentially tens of thousands of additional migrant families, Barr delayed the start of the new rule until July. But Thursday's legal challenge tries to stop the new rule from ever going into effect.

Michael Tan, an attorney with the ACLU's Immigrants’ Rights Project and one of the lawyers who filed the challenge in federal district court in Seattle, said Barr's ruling is a clear violation of the Constitution and the 5th Amendment, which states that people cannot be deprived of life, liberty or property without due process under the law.

If Barr's rule goes into effect, the only option for asylum seekers to be released from detention is requesting parole directly from Immigration and Customs Enforcement, or ICE, which generally houses most immigration detainees. That option, Tan argued, is nothing more than a "sham" since ICE is a law enforcement agency that has "an institutional bias in favor of locking people up."

"The attorney general's decision is just part of this overall assault we've seen from this administration against asylum seekers and the asylum system," Tan said. "They know there's no good reason to lock up a lot of these people."

Barr's proposed rule is the latest attempt by the Trump administration to unilaterally change asylum rules in an attempt to stop the record-setting flow of Central American migrants crossing the southern border. Those attempts have received mixed results once they've been challenged in court.

In June, then-Attorney General Jeff Sessions barred victims of domestic abuse and gang violence from applying for asylum. That decision was blocked by a federal judge.

In November, the departments of Justice and Homeland Security issued new rules that barred migrants who entered the U.S. illegally from applying for asylum. That decision also was blocked by a federal judge.

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In December, then-Secretary of Homeland Security Kirstjen Nielsen announced a plan barring Central American asylum seekers from entering the U.S. and ordering them to remain in Mexico while their cases are decided. That was initially blocked by a federal judge, but was temporarily revived by the U.S. Court of Appeals for the 9th Circuit.

And on Monday, the president ordered his departments of Justice and Homeland Security to issue sweeping new rules that would make it more difficult, and more expensive, for asylum seekers to seek refuge in the U.S. The rules would, for the first time, require asylum-seekers to pay an application fee, deny work permits for asylum-seekers who enter the country illegally and require government officials to fast-track new asylum hearings to complete them within 180 days.

Those new rules are also expected to be challenged in court.

Thursday's legal challenge was filed in an ongoing lawsuit in Seattle challenging the slow pace of bond hearings for asylum seekers already in custody. On April 4, U.S. District Judge Marsha Pechman ordered the administration to provide bond hearings within seven days, and placed the burden of proof on the Department of Homeland Security, not the asylum seekers, to justify the continued detention.

Now, the ACLU, the American Immigration Council, and the Northwest Immigrant Rights Project are asking Pechman to halt Barr's new rule expanding detention for asylum seekers.