Immigrants already in the United States under temporary status seeking to become legal permanent residents will now have to return to their home country to begin the application process, U.S. Citizenship and Immigration Services announced in a memo released on Friday.

The policy memo, addressed to USCIS officers, says that immigrants seeking a green card must return to their country of origin to apply, except in “extraordinary circumstances.”

For years, immigrants have been able to legally file for immigration status adjustments while remaining in the United States. While their change in status is pending, many have been able to receive temporary work and travel permits. Under the new directive, if immigrants look to become permanent residents, those would no longer be options — and in order to apply for permanent status, they would have to return to their country of origin.

In practice, the move could require thousands of people who have been lawfully present in the country — no matter for how long —- to apply for a green card in a different country, a process that can take years. The policy would also mean that because the applicant would be outside of the country, the State Department would review the decisions through an embassy or consulate, as opposed to through USCIS. Decisions made by State Department consular offices abroad are much more difficult to challenge.

Azadeh Erfani, policy director at the National Immigrant Justice Center, told NOTUS that the change will upend the lives of families who have been in the country for years and is effectively a backdoor, family-separation policy. It could also make more challenging the more common pathways to legal status such as marriage or long ties in the country.

“People often wait years to be able to seek an appointment with what’s called consular processing to go through a consulate in order to come back into the United States with a green card,” Erfani said. “This line is so long that people have died waiting.”

Zach Kahler, a spokesperson for USCIS, wrote in a statement that the policy change was “returning to the original intent of the law.”

“This policy allows our immigration system to function as the law intended, instead of incentivizing loopholes,” said Kahler. “When aliens apply from their home country, it reduces the need to find and remove those who decide to slip into the shadows and remain in the U.S. illegally after being denied residency.”

The memo acknowledges situations like dual intent, when immigrants hold temporary visas while seeking permanent status.

But in the footnotes, the agency adds a caveat: “maintaining lawful status in a dual intent nonimmigrant category is not sufficient, on its own, to warrant a favorable exercise of discretion.”

Throughout both terms, President Donald Trump has aggressively targeted undocumented immigrants. But he has also increasingly eyed sweeping, restrictive changes to the pathways for legal immigration.

In February, USCIS and Immigration and Customs Enforcement released a memo to federal agents instructing them to arrest refugees without a green card. Refugees, under U.S. law, have a year to file for a green card, a timeline also more strictly enforced by the Trump administration. And other legal pathways have had significant policy changes, including a pause on work permits for asylum seekers and the deportation of dozens of people covered under the Deferred Action for Childhood Arrivals program.

The decision by the administration could prompt legal challenges, although Erfani told NOTUS, “it’s too soon to say.”

“This is stretching the law beyond how it was intended to function,” Erfani said. “There’s too many people who are impacted for there to not be more legal challenges.”