The US Supreme Court has left in place for the time being a pandemic-era order allowing officials to rapidly expel migrants caught at the Mexico border so it can consider whether 19 states can challenge the policy’s end.

The court on a 5-4 vote granted a request by a group of Republican state attorneys general to put on hold a judge’s decision invalidating the emergency order, known as Title 42, while it considered whether they could intervene to challenge the ruling.

The states had argued lifting the policy could lead to an increase in record border crossings.

On December 19, Chief US Supreme Court Justice John Roberts, a member of the court’s 6-3 conservative majority, issued a temporary administrative stay maintaining Title 42 while the court considered whether to keep the policy in place for longer.

The policy had initially been set to expire on December 21.

Conservative Justice Neil Gorsuch joined with the court’s three liberal members – Justices Sonia Sotomayor, Elena Kagan Ketanji Brown Jackson – in dissenting from Monday’s order leaving Title 42 in effect.

The Title 42 order was first implemented in March 2020 under Republican former president Donald Trump at the beginning of the COVID-19 pandemic.

US President Joe Biden, a Democrat, kept the restrictions in place for more than a year after taking office in 2021, despite promising to shift away from hardline immigration policies adopted by Mr Trump.

US Border Patrol agents apprehended a record 2.2 million migrants at the south-west border in the year to September 30. Almost half of those arrested were rapidly expelled under the Title 42 policy.

-AAP