Plaintiffs led by the American Civil Liberties Union (ACLU) filed a suit against the Trump administration in US District Court in San Francisco on Tuesday in an attempt to halt the implementation of a new policy disqualifying most asylum seekers who pass through Mexico before reaching the United States.

The attorneys suing the government argued in their complaint that the Trump administration lacks the authority to exclude asylum seekers who arrive across the US southern border because US immigration law states clearly that the government cannot disqualify applicants on the basis of how they arrived.

“As part of our nation’s commitment to the protection of people fleeing persecution and consistent with our international obligations, it is long-standing federal law that merely transiting through a third country is not a basis to categorically deny asylum to refugees who arrive at our shores,” the complaint states.

A separate petition seeking an injunction against the asylum change was filed by two other immigrant rights groups in the US District Court in Washington on Tuesday evening.

The lawsuits came just hours after the Justice and Homeland Security departments published an “interim final rule” in the Federal Register that aims to severely restrict the ability of asylum seekers to qualify for safe haven in the United States if they failed to request protections in other nations while en route to the border.

'Dangerous' overcrowding of migrants in US border facilities Show all 6 1 /6 'Dangerous' overcrowding of migrants in US border facilities 'Dangerous' overcrowding of migrants in US border facilities Photos of detained migrants crowded into cells at the US border - with one holding up a sign reading simply "help" - have been released as part of a new report warning of "dangerous" overcrowding. The memo was sent to the Department of Homeland Security by its Inspector General, containing photos taken at border facilities in the Rio Grande Valley over a week in June DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Eighty-eight adult males held in a cell with a maximum capacity of 41, some signalling prolonged detention to OIG Staff on June 12 DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Overcrowding of families observed by OIG on June 11, at a border patrol facility in Weslaco, Texas DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Migrant families overcrowding a border patrol facility on June 11 in McAllen, Texas DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Fifty-one adult females held in a cell designated for male juveniles with a capacity for 40 at Border Patrol’s Fort Brown Station DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Migrant families overcrowding a border patrol facility on June 11 in McAllen, Texas DHS/OIG

Attorney General William Barr said in a statement on Monday that those who are truly facing persecution should apply for refuge in the first safe place they reach, not the most desirable destination.

He likened the surge of asylum claims at the US southern border to “forum shopping” by applicants attempting to exploit American generosity.

Trump administration officials said the policy decree was needed to shore up the overburdened US asylum system from a flood of meritless claims by migrants who are seeking better economic opportunity but do not face actual persecution.

Justice Department data shows that asylum filings have nearly quadrupled in the past five years and that fewer than 20 per cent of Central American applicants are eventually granted protections by US courts.

The ACLU and others seeking to block implementation of the restrictions allege that the Trump administration violated federal rulemaking procedures in formulating them, and that the Immigration and Nationality Act states clearly that once applicants reach US soil, they have a right to appeal for protection.

Lee Gelernt, the ACLU attorney who has led the group’s legal challenges to Trump executive action on immigration, called it “the Trump administration’s most extreme run at an asylum ban yet.”

“It clearly violates domestic and international law, and cannot stand,” Mr Gelernt said in a statement.

The Southern Poverty Law Centre, the Centre for Constitutional Rights and others joined the ACLU in seeking the injunction in the US District Court for the Northern District of California.

The court is within the jurisdiction of the US Court of Appeals for the 9th Circuit, which has been the forum for nearly all of the major immigration litigation challenging Mr Trump.

The court has a reputation as the country’s most liberal, and administration officials say the ACLU and its fellow plaintiffs are practising their own version of “forum shopping” by reliably suing in California.

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In the Washington lawsuit, the plaintiffs, Capital Area Immigrants’ Rights Coalition and Refugee and Immigrant Centre for Education and Legal Services said the new rule “creates a new third country-related exception to the (act’s) presumption of asylum eligibility for those in the United States”.

As of Tuesday afternoon, it was unclear whether the government had begun denying asylum at the border under the new rule.

The change potentially allows the government to deport those who request asylum back to their home countries if they declined to appeal for safe harbour in Mexico or another transit nation.

The rule includes exceptions for trafficking victims and those denied refuge by other governments.

A federal judge in San Francisco last year blocked the Trump administration’s attempt to enact a similar asylum change.

It would have disqualified applicants who cross the border illegally between ports of entry, but the court ruled that the president “may not rewrite the immigration laws to impose a condition that Congress has expressly forbidden”.