Asylum seeking migrants from Central America sit next to a vehicle that was stopped by police after crossing the Rio Grande into Eagle Pass, Texas from Mexico along U.S. Route 90, in Hondo, Texas, U.S., June 1, 2022.  U.S. authorities, blocked by a federal judge from lifting COVID-19 restrictions that empower agents at the U.S.-Mexico border to turn back migrants, continue to enforce the Title 42 rules which result in the fast expulsion of migrants to Mexico or other countries.   REUTERS/Shannon StapletonAsylum seeking migrants from Central America sit next to a vehicle that was stopped by police after crossing the Rio Grande into Eagle Pass, Texas from Mexico along U.S. Route 90, in Hondo, Texas, U.S., June 1, 2022. 

The Trump-era rule that allows Customs and Border Patrol officials to deport migrants at the U.S. southern border as a public health measure was upheld by the Supreme Court.

The 19 Republican state attorneys general were granted an emergency request by the court. The Supreme Court will decide by the end of June whether the states can intervene in the case. Until that ruling is issued, the policy will continue.

The conservatives on the court voted against the stay request. The federal government can still take action with respect to the Title 42 policy despite the administration's inability to set aside it.

Since 2020, more than two million people have been deported at the southern border.

Supreme Court Chief Justice John Roberts stopped the policy from being ended.

A federal district court in D.C. ordered the Department of Homeland Security to stop the deportations. Republican states petitioned the Supreme Court to stop the lower court ruling.

The policy was started by the Trump administration. In March 2020 the Centers for Disease Control and Prevention used a provision under the Public Health Services Act to prohibit migrants from crossing into the US from Mexico or Canada. Title 42 is the name of the policy.

Human rights groups and dozens of health experts denounced the policy as a way for the federal government to carry out arbitrary mass deportations at the U.S. southern border.

When the CDC said it was necessary to prevent the spread of Covid, the Biden administration stopped the policy. Republican states got a federal court in Louisiana to stop the Biden administration from ending the deportations at the same time as the CDC and DHS had planned.

Republicans and some Democrats believe that ending the policy will lead to an increase in migration at the southern border. The state of emergency was declared in El Paso, Texas due to an increase in migrants crossing the border.

NBC News made a contribution to the report.