The US Supreme Court has cleared the way for President Donald Trump to use a rarely-invoked wartime powers law to rapidly deport alleged gang members - for now.

A lower court had temporarily blocked the deportation of alleged Venezuelan gang members to El Salvador on 15 March, ruling that the actions under the 1798 Alien Enemies Act needed further scrutiny.

Trump has alleged that the migrants were members of the Tren de Aragua gang "conducting irregular warfare" against the US and could therefore be removed under the Act.

While the administration is claiming the ruling as a win, the justices mandated that deportees must be given a chance to challenge their removal.

"The notice must be afforded within a reasonable time and in such a manner as will allow them to actually seek habeas relief in the proper venue before such removal occurs," the justices wrote in the unsigned decision on Monday.

"The only question is which court will resolve that challenge," they wrote.

Monday's ruling said the challenge - brought by the American Civil Liberties Union (ACLU) on behalf of five migrants - was raised improperly in a Washington DC court and not in Texas, where the migrants are confined.

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Conservative Justice Amy Coney Barrett joined the court's three liberal justices in dissenting with the majority ruling.

In the dissent, they wrote that the administration's "conduct in this litigation poses an extraordinary threat to the rule of law".

Trump called the ruling a "great day for justice in America".

"The Supreme Court has upheld the Rule of Law in our Nation by allowing a President, whoever that may be, to be able to secure our Borders, and protect our families and our Country, itself," he wrote on Truth Social.

The ACLU also claimed the ruling as "a huge victory".

"We are disappointed that we will need to start the court process over again in a different venue but the critical point is that the Supreme Court said individuals must be given due process to challenge their removal under the Alien Enemies Act," lead ACLU attorney Lee Gelernt said in a statement to US media.

At least 137 people have been deported by the Trump administration under the Alien Enemies Act, a move widely condemned by rights groups.

The act, last used in World War Two, grants the US president sweeping powers to order the detention and deportation of natives or citizens of an "enemy" nation without following the usual processes.

It was passed as part of a series of laws in 1798 when the US believed it would enter a war with France.

The Trump administration says all the deportees are members of the Tren de Aragua gang. The powerful multi-national crime group, which Trump recently declared a foreign terrorist organisation, has been accused of sex trafficking, drug smuggling and murders both at home and in major US cities.

US immigration officials have said the detainees were "carefully vetted" and verified as gang members before being flown to El Salvador, under an agreement with that country.

But many of the deportees do not have US criminal records, a US Immigration and Customs Enforcement (ICE) official acknowledged in court documents.

Some relatives of the deported migrants have told the BBC the men have been wrongly swept up in the immigration crackdown, and that they are innocent.

Several other families have said they believe that deportees were mistakenly identified as gang members because of their tattoos.

Monday's decision vacates an earlier ruling by federal judge James Boasberg, later upheld by a federal appeals court, which had temporarily blocked the use of the law to carry out the deportations.

Boasberg had dismissed the government's response to his order as "woefully insufficient". The White House had said the judge's order itself was not lawful and was issued after two flights carrying the men had already left the US.

Rights groups and some legal experts have called the invocation of the Act unprecedented, arguing it has only previously been used after the US officially declared a war, which under the US constitution only Congress can do. (BBC)

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