Washington DC - Following a last-ditch appeal by some Republican-controlled states, the Supreme Court has stepped in to block the expiration of the Title 42 immigration policy, which was set for Wednesday.

Chief Justice John Roberts on Monday issued an order putting a temporary stop to plans to phase out Title 42, a Trump-era public health order that denies migrants crossing the Southern border the right to apply for asylum in the US and allows US officials to expel them either to Mexico or their countries of origin.

The measure was ostensibly passed in an effort to prevent the spread of Covid-19 but has been criticized as a breach of migrants' basic rights. According to US Customs and Border Protection data, the policy has already been used to expel migrants over 2.5 million times since March 2020.

A federal judge had called for an end to the program in November, ruling it to be "arbitrary and capricious." A deadline was set for December 21, 2022.

The Supreme Court's latest announcement is not a final ruling on the question, and the Biden administration has said it is continuing its preparations for Title 42 to end.

"As required by the Supreme Court’s administrative stay order, the Title 42 public health order will remain in effect at this time and individuals who attempt to enter the United States unlawfully will continue to be expelled to Mexico," the Department of Homeland Security said in a statement on Monday. "While this stage of the litigation proceeds, we will continue our preparations to manage the border in a safe, orderly, and humane way when the Title 42 public health order lifts."

The Biden administration was given until 5:00 PM EST on Tuesday to respond to the appeal.