Friday's agreement by the justices allowed them to hear the administration’s appeal against lower court rulings which forced it to reinstate "Remain in Mexico” policy, which was introduced in 2019 by former President Donald Trump. Arguments will be held in April with a decision expected by June.

The program was formerly known as Migrant Protection Protocols. President Joe Biden suspended it on his first day of office. Homeland Security Secretary Alejandro Mayorkas ended the program in June 2021.

After the Republican-led Texas and Missouri sued Biden over his action, a federal court ordered that the policy be reinstated and a three-judge appeals panel agreed. Trump appointed the district judge and two of three appellate judges.

Mayorkas acknowledged that there was a decrease in illegal border crossings in 2019. However, he said there were "substantial" and "unjustifiable human cost" for asylum-seekers who were subject to violence while they waited in Mexico.

Although the program is now being resumed, it is slowing down. According to the United Nations migration agency, 572 people were returned to Mexico since December's restart.

Trump and Biden used separate authorities to expel over 1.5 million migrants from March 2020. This authority was aimed at stopping the spread of COVID-19. They did not give them the opportunity to claim asylum.