Over three years after the Migrant Protection Protocols (MPP) went into effect, the Supreme Court finally heard oral arguments in a case about the program, also known as the “Remain in Mexico” policy. Rather than debate the legality of the program itself, Tuesday’s arguments were about a different question altogether: whether the Biden administration has the legal authority to end it.

Unlike in the prior DACA case, when observers generally agreed that the Trump administration could end DACA if it went through the right procedures, the state of Texas successfully obtained a court order blocking the Biden administration from ever ending MPP. Going even further, the 5th Circuit Court of Appeals refused to even consider Department of Homeland Security (DHS) Secretary Mayorkas’ second attempt to end the program in compliance with the original court order.

At oral arguments in front of the Supreme Court, many justices were skeptical of Texas’ arguments that the Biden administration was required to keep MPP in place. The Immigration and Nationality Act (INA) only says that DHS “may” use the legal authority behind MPP.

Multiple justices also pointed out that under Texas’ arguments, even the Trump administration would have been violating the law. The former administration used MPP for a relatively small number of people crossing the border and exempted entire classes of people from being returned to Mexico.

Under questioning from Justice Thomas, Texas Solicitor General Judd Stone agreed that the state of Texas could have sued the Trump administration when it put MPP into place. However, he said they probably wouldn’t have sued because the Trump administration’s violation was to a lesser degree.

Justice Roberts expressed a lot of skepticism to this response, saying “I think it’s a bit much for Texas to substitute itself for the Secretary and say that you may want to terminate this, but you have to keep it, because it will reduce to a slight extent your violations of the law.”

Stone also faced significant pushback on his attempt to argue that the lower court’s order doesn’t force the Biden administration to negotiate with Mexico. At one point, when Stone argued that the order itself doesn’t mention Mexico, Justice Kagan laughed and asked him, “What are we supposed to do, just drive truckloads of people into Mexico without negotiating with Mexico?”

Despite the skepticism of much of Texas’ arguments, multiple justices expressed concern that the Biden administration was releasing too many people at the border. Even though Texas had previously disclaimed any challenge to the Biden administration’s use of parole to release people at the border, questions about parole dominated the arguments. Kavanaugh even said he believed the scope of DHS’ authority to release people on parole was at the “heart of the matter.”

Under the law, DHS may release any individual on parole if it determines that there is “significant public benefit” to doing so. Since that law was passed in 1996, the government has long determined that it can consider detention capacity when deciding on a case-by-case basis whether to grant parole.

Texas argued that considering detention capacity when deciding to grant parole is illegal. That argument didn’t appear to get much support from the justices. Justice Barrett noted that Texas would likely lose the case if the Supreme Court disagreed with them on the scope of the parole power, and Justice Kavanaugh emphasized that courts usually give a lot of discretion to the executive branch to determine when something is in the “public benefit.”

The current state of renewed MPP under the Biden administration didn’t come up much at the court, except for Solicitor General Prelogar’s observations that keeping MPP in place imposes enormous fiscal and diplomatic costs on the United States.

Although the Justices seemed to care little about the practical realities of MPP, the program continues to grow every day. Last month, nearly 1,000 people were returned to Mexico under the program. And on April 21, the Biden administration announced the creation of a website where people returned to Mexico could file requests to be taken out of the program or given new screenings for fear of persecution in Mexico.

The Supreme Court is unlikely to issue a decision until late June. Even a decision in favor of the Biden administration doesn’t mean that MPP will be terminated. At that point, the lower court would still have to consider the Biden administration’s renewed October 2021 attempt to terminate MPP. Despite the October memo not being before the court, Justice Kavanaugh expressed significant skepticism that the Biden administration had explained itself enough in its 39-page memo terminating the program.

Unfortunately, that suggests that even a victory for the Biden administration in this case may not be enough in the long run to end MPP.