A federal appeals court on Friday cleared the way for the U.S. government to forbid Central American immigrants from seeking asylum at the two busiest stretches of the southern border in a partial legal victory for the Trump administration.

The ruling from the 9th U.S. Circuit Court of Appeals allows President Donald Trump to enforce the policy in New Mexico and Texas, rejecting asylum seekers who cross from Mexico into either state. Under Friday’s ruling, U.S. District Judge Jon Tigar’s July 24 order stopping the policy would apply only in California and Arizona, which are covered by the 9th Circuit.

The two busiest areas for unauthorized border crossings are in South Texas’ Rio Grande Valley and the region around El Paso, Texas, which includes New Mexico. Nearly 50,000 people in July crossed the U.S. border without permission in those two regions, according to the U.S. Border Patrol.

The policy would deny asylum to anyone who passes through another country on the way to the U.S. without seeking protection there. Most crossing the southern border are Central Americans fleeing violence and poverty, who would largely be ineligible. The policy would also apply to people from Africa, Asia, and South America who come to the southern border to request asylum.

If the policy is implemented, ineligible migrants who cross in New Mexico and Texas could be detained and more quickly deported. The U.S. Department of Homeland Security did not immediately respond to a request for comment Friday.

Under American law, people can request asylum when they arrive in the U.S. regardless of how they enter. The law makes an exception for those who have come through a country considered to be “safe” pursuant to an agreement between the U.S. and that country.

Canada and the U.S. have a “safe third country” agreement. But the U.S. doesn’t have one with Mexico or countries in Central America. The Trump administration has tried to sign one with Guatemala, but the country’s incoming president said this week that Guatemala would not be able to uphold a tentative deal reached by his predecessor.