(NewsNation) — The issue of what to do with people who present themselves at the U.S. southern border seeking asylum has long been a thorny one: Should they be welcomed into the country while their cases are heard, or should they have to wait until that hearing before gaining admittance?

Now, the U.S. Supreme Court is getting into the debate, as the number of people stopped at the southern border hit 221,000 in March, and 66,000 of those were allowed into the U.S.

The court Tuesday heard arguments over whether the Biden administration can end the Trump-era immigration policy known as “Remain in Mexico.” The policy forces those seeking asylum to remain on the Mexican side of the border while waiting for their cases to be adjudicated. Former President Donald Trump instituted the policy in 2019 to stem the flow of those seeking entry to the U.S. at the southern border.

“These are big issues of executive power and the legality of immigration causes. But ultimately, it’s a human issue,” said Sabrina Talukder, Sunita Jain Anti-Trafficking Policy Initiative federal policy director at Loyola Law School.

President Joe Biden sought to end “Remain in Mexico” on his first day in office. However, two states, Texas and Missouri, sued. Lower courts reinstated the order.

Talukder says the main issue isn’t just about getting rid of the policy but the fact that a lower-level court can block a decision backed by the American people. “The American people voted for President Biden and one of his campaign promises was to rescind the ‘Remain in Mexico’ program. The lower court judge doesn’t get to tell the Biden administration what the American people did and didn’t vote for,” she said.

Advocates for the lower court say the Biden administration needs to follow federal law and detail asylum-seekers or send them back to their country of origin. Supreme Court Justice Sonia Sotomayor countered, saying that can’t happen without the cooperation of Mexico. “What are we supposed to do? Just drive truckloads of people into Mexico and just leave them without negotiating with Mexico?” she asked.

Since the police was enacted, 68,000 migrants have been subject to it. The debate unfolds as the number of migrants crossing into the U.S. reaches a record high.

The Biden administration has pledged to work on a root cause strategy to address migration and enhance legal avenues for those in need of protection. This includes looking at issues in the “Northern Triangle” of countries made up of Honduras, El Salvador and Guatemala.

A decision from the court is not expected before the end of June.