The United States Supreme Court on Thursday ruled that migrants who apply from the Mexican side of the U.S. border would not be eligible for asylum unless they cross into the country.

The 6-3 verdict allows President Donald Trump’s administration to block asylum seekers at the border amid its immigration crackdown after it sought to reinvigorate the 2016 “metering” policy.

The case centres on whether migrants on the Mexican side of the border can be considered to have arrived in the U.S. or only after physically crossing the border.

The Immigration and Nationality Act (INA) provides that an alien who “arrives in the United States” may apply for asylum and must be inspected, but the Trump administration maintained that foreign nationals turned back before entering the country are ineligible to apply for asylum.

Justices Samuel Alito, John Roberts, Clarence Thomas, Neil Gorsuch, Brett Kavanaugh, and Amy Coney Barrett joined the majority opinion, while Elena Kagan, Ketanji Brown Jackson, and Sonia Sotomayor disagreed.

“The wisdom of the policy of metering alien arrivals at the southern border is not before us,” Mr Alito, who delivered the court’s opinion, wrote.

“We decide only that an alien standing in Mexico does not ‘arrive in the United States’. The INA neither entitles such an alien to apply for asylum nor requires an immigration officer to inspect him.”

However, Ms Sotomayor argued that the decision would deny asylum seekers protections guaranteed under U.S. law by preventing them from entering the country, noting, “The consequences of today’s decision are predictable.”

“They may do so even if the asylum seeker is at the threshold of a port of entry designated to receive all noncitizens who seek entrance into the country.

“Even if the port of entry has ample capacity to inspect that person, including an available asylum officer trained to process asylum applications. Even if the asylum seeker is certain to be persecuted or killed, if she is turned away,” she said.

The Department of Homeland Security first adopted the “metering” policy in 2016, following a surge in admissions at the U.S.-Mexico border. Then, officials limited the number of migrants seeking asylum and prevented others from entering the country beyond the number of ports of entry capable of processing them.

Former President Joe Biden’s administration rescinded the policy in 2021.

Amid its crackdown on immigration, the Trump government asked the apex court in March to revive the 2016 policy to address the influx of migrants into the U.S.

An appeals court also ruled in April that the government would not categorically deny asylum to migrants crossing into the U.S. from Mexico.

Since returning to the White House last year, Mr Trump has moved to limit immigration into the U.S., citing a high rate of visa overstays and identity fraud, among other issues.

A humanitarian group, Al Otro Lado, and a group of asylum seekers filed the case in 2017 during Mr Trump’s first administration, when migrants were turned back at the border. 

Critics said the asylum seekers were left stranded at temporary housing.