When a woman gashed her leg in mountains inhabited by snakes and scorpions, she told Joel Úbeda to take her 5-year-old daughter. Úbeda refused to let the mother die, despite the advice of their smuggler and another migrant in a group of seven, and helped carry her to safety by shining a mirror in sunlight to flag a U.S. Customs and Border Protection helicopter near San Diego.

The motorcycle mechanic, who used his house in Nicaragua as collateral for a $6,500 smuggling fee, says the worst day of his life was yet to come.

Arrested after the encounter with U.S. agents, Úbeda learned two days later that he could not pursue asylum in the United States while living with a cousin in Miami. Instead, he would have to wait in the Mexican border city of Tijuana for hearings in U.S. immigration court under a Trump-era policy that will be argued Tuesday before the U.S. Supreme Court.

President Joe Biden halted the “Remain in Mexico” policy his first day in office. A judge forced him to reinstate it in December, but barely 3,000 migrants were enrolled by the end of March, making little impact during a period when authorities stopped migrants about 700,000 times at the border.