A US federal judge on Monday blocked President Donald Trump's policy of returning asylum seekers to Mexico to wait out the processing of their cases, saying the Department of Homeland Security had overstepped its authority.
The ruling by US District Judge Richard Seeborg in San Francisco marked a rebuke for the Trump administration's efforts to stop the flow of migrants seeking asylum through the US border with Mexico.
The decision, which goes into effect on Friday, also comes just days after outgoing Homeland Security Secretary Kirstjen Nielsen had vowed to expand the controversial program.
Several hundred people seeking asylum have been returned to Mexico to await the outcome of their request under the policy first implemented in January at the San Ysidro port of entry in California and later extended to Calexico, a second California border point, and El Paso, Texas.
Rights groups welcomed the ruling on Monday, saying the return policy known as Migrant Protection Protocols (MPP) failed to provide adequate safeguards to protect asylum seekers from persecution.
"The court strongly rejected the Trump administration's unprecedented and illegal policy of forcing asylum seekers to return to Mexico without hearing their claims," said Judy Rabinovitz, deputy director of the ACLU's Immigrants' Rights Project.
"Try as it may, the Trump administration cannot simply ignore our laws in order to accomplish its goal of preventing people from seeking asylum in the United States.
The ACLU and several other groups, including the Southern Poverty Law Center, had sought an injunction against the policy on behalf of 11 asylum seekers from El Salvador, Honduras and Guatemala who were returned to Mexico after seeking asylum at the US border.
In his 27-page ruling, Seeborg said at issue was not whether the MPP is "a wise, intelligent, or humane policy" but rather whether it exposes aliens to "unduly dangerous circumstances."
He noted that the plaintiffs in the case were not challenging the "system" of expedited removal.
- Facing persecution -
"Indeed, in essence, plaintiffs are arguing that because they are subject to expedited removal, they should at a minimum have the protections they would enjoy under that regime, either by being exempt from contiguous territorial return, and/or by having additional procedural and substantive protections against being sent to places in which they would not be safe from persectuion," the judge wrote.
There was no immediate reaction from the Department of Homeland Security or Trump on the ruling, which can be appealed.
Trump, who originally dubbed the measure the "Remain in Mexico" policy, unveiled it last year as a series of caravans with thousands of Central American migrants made their way to the US-Mexican border.
He called the caravans an "invasion" by "thugs" and "criminals," and regularly pointed to them as evidence in support of his declaration of a national emergency on the southern border and plans to build a wall there.
Mexico said it was cooperating with US authorities concerning the migrants being sent back, but only for humanitarian reasons.
Migrants who reach US soil have a legal right to seek asylum and are usually held in detention facilities while their application is processed or released into the United States.