This rule, first implemented by former President Donald Trump, requires migrants who arrive at the southern border to remain outside the U.S. in order to receive asylum hearings.

The case is known as Biden V. Texas. It centers on the decision by President Biden's appointees last year to suspend and eventually end the policy. This policy was used by the Trump administration to force 70,000 Latin American migrants from Latin America to wait outside the U.S. to await asylum applications were processed.

Formerly known as the Migrant Protection Protocols. The Trump administration reduced the rule when the COVID-19 pandemic began, and Mr. Biden ended the program upon his assumption of office. Republican officials from Texas persuaded a federal judge to order U.S. Border officials to reinstate it in August 2021.

U.S. Judge Matthew Kacsmaryk was a Trump appointee. He ruled that the administration had not adequately justified Remain in Mexico's termination, and that officials violated a 1996 law that mandates the detention of certain immigrants.

The border policy has been implemented by the Biden administration since December. However, it was only limited. It has maintained its argument that it has the power to end the program, and denounced the "unjustifiable human cost" it imposes on asylum-seekers.

Lawyers for the Justice Department, who requested that the Supreme Court intervene on an expedited basis in the case, will argue Tuesday that the executive has broad authority to repeal policies passed by previous administrations.

The Justice Department lawyers stated that the conclusions of the lower courts meant that all U.S. administrations have been in "open and systemic violations" of the 1996 migrant-detention law. This was because only Trump had implemented the Remain in Mexico policy. It wasn't until the beginning 2019.

Biden's administration also stated that it was logistically impossible for all migrants to be detained at the U.S.-Mexico frontier, as Congress only has funds for 34,000 detention beds.

However, Texas lawyers argue that U.S. border officers are required to detain and return migrants to Mexico. Texas argued that if the U.S. is unable to detain migrants due to capacity limitations, it should return them back to Mexico so they can await their asylum cases.

"Petitioners would prefer to not choose from the options Congress provides -- namely to detain or individually parole or return covered aliens. Instead, they seek to have the power to allow certain classes of aliens into America en masse," Texas stated in an April 7 filing.

The Supreme Court will be examining two specific questions: whether to overturn the conclusion of the 5th Circuit Court of Appeals that Remain in Mexico officials must enforce to comply with 1996 migrant detention laws, and whether the appeals court should consider the second attempt by the Biden administration to end the policy.

The 5th Circuit affirmed the December order against Remain in Mexico's cancellation. It rejected the argument that Secretary Alejandro Mayorkas, Department of Homeland Security (DHS), had issued a second termination notice to correct the legal flaws in his original termination memo.

The court stated in its harsh opinion that DHS claimed the power to reverse a major policy -- which could have a huge impact on billions of dollars and countless others -- by simply typing a Word document into a new Word document, and then posting it online.

The Biden administration reinstated the rule in December. It has now enrolled 3,012 immigrants in the Remain in Mexico program. Most of these migrants are asylum-seekers from Venezuela, Nicaragua, and Cuba, DHS data. Over 700,000 migrants were processed by U.S. border officials during that time.

Although Mr. Biden sought to end Remain in Mexico, his administration maintained another Trump-era border policy called Title42. This policy allowed U.S. officials and agents to quickly expel migrants from the United States without screening them for asylum. Title 42 will expire in May.

Advocates for migrants were critical of the Trump administration's implementation Remain in Mexico. They claimed that the rule left asylum seekers at the mercy criminal groups in dangerous Mexican border communities. Human Rights First, an American group, reported hundreds upon cases in which migrants were kidnapped and assaulted after they returned to Mexico.

Advocates claimed that the program violated the rights of asylum-seekers. An analysis of government information by Syracuse University's TRAC Project shows that less than 800 migrants who enrolled in Remain in Mexico protocols were granted U.S. asylum. Tens of thousands of them lost their cases or were deported because they missed court dates.

Officials from the Trump administration claimed that the program reduced border arrivals because it prevented migrants fleeing poverty from applying for asylum to stay and work in the U.S.

The Biden administration made important changes in its iteration Remain in Mexico program. This included requiring U.S. border officers to ask migrants if they fear being hurt in Mexico before they send them there.

The administration also provided COVID-19 vaccinations to potential enrollees. It also expanded the categories for asylum-seekers who were deemed too vulnerable to be returned home to Mexico, such as the elderly and those with serious medical conditions.