(NewsNation) —  The Supreme Court heard arguments on the Biden administration’s efforts to end a controversial Trump-era immigration policy.

The policy, called “Migrant Protection Protocols,” also known as the “Remain in Mexico” program, requires asylum seekers at the U.S. border to wait in Mexico while their cases are processed. 

Here is what we know:

• More than 71,000 people had been processed under the program since the policy was introduced, according to the Trac database.
• Former President Donald Trump instituted the policy in 2019 to deter migrants from applying for asylum.
• President Joe Biden attempted to end the policy on day one of his term.
• Lower courts ordered it be reinstated after Texas and Missouri sued.
• Advocacy groups say the policy subjects migrants to inhumane and dangerous conditions.

Now, how large is that out of the overall immigration program?

• The U.S. Solicitor General told the Supreme Court that the Department of Homeland Security processed more than 671,000 migrants under the traditional process last year

• For comparison’s sake, in 2020, which was the last year the “Remain in Mexico” program was in full effect, 20,000 migrants were processed under that program

Overall “Remain in Mexico” has been a small percentage of the immigration processing actions, especially after the introduction of Title 42, which had most immigrants turned away without being able to apply for asylum