The Biden administration on Friday announced its second attempt to end a Trump-era border program that forced migrants to wait in Mexico for their U.S. asylum hearings, issuing a new termination memo it hopes will pass legal muster.

In his memo, Department of Homeland Security Secretary Alejandro Mayorkas conceded the so-called “Remain in Mexico” policy — officially known as the Migrant Protection Protocols, or MPP — likely reduced unauthorized migration to the U.S.-Mexico border during the Trump administration. But he said the program’s humanitarian implications on the tens of thousands of migrants who were returned to Mexico outweighed its deterrence effect.

“I recognize that MPP likely contributed to reduced migratory flows. But it did so by imposing substantial and unjustifiable human costs on the individuals who were exposed to harm while waiting in Mexico,” Mayorkas wrote in his four-page memo.