The U.S. Department of Justice (DOJ) announced last month that it had created a standalone denaturalization section to strip citizenship from naturalized immigrants, as part of the Trump administration’s broad pushback on immigration.

The denaturalization section “underscores the department’s commitment to bring justice to terrorists, war criminals, sex offenders, and other fraudsters who illegally obtained naturalization,” the department said in a press release.  “The Denaturalization Section will further the Department’s efforts to pursue those who unlawfully obtained citizenship status and ensure that they are held accountable for their fraudulent conduct.”

Denaturalization cases require that the government show that citizenship was obtained illegally—i.e., the defendant did not actually meet the legal requirements of citizenship—or, second, the defendant’s naturalization was “illegally procured” or procured by concealment of a material fact or by willful misrepresentation. The concealment or misrepresentation of a material fact can be made during the naturalization interview or on the naturalization application. In Maslenjak v. United States (2017), for example, Divna Maslenjak, a refugee from the former Yugoslavia, was stripped of her citizenship and deported because immigration officials discovered that she had made false statements during her naturalization process. Maslenjak admitted that she had lied, but she argued that she should be able to keep her citizenship because her lies were not material—that is, they would not have mattered to immigration officials. The Supreme Court agreed with Maslenjak, holding that her lies can be held against her only if they would have been important to the officials deciding whether to grant her citizenship. In other words, the government must prove that the false statement influenced the citizenship process.

There is no statute of limitations on civil denaturalization cases, meaning that the government can take away citizenship decades after a person became an American citizen. Nor does it matter whether the individual has built an exemplary life in the United States after being granted citizenship.

Critics say that the new DOJ office could be used against immigrants who have not committed serious crimes and will also likely inspire fear in immigrant communities. In particular, there are fears that this effort will have a serious chilling effect on the number of legal permanent residents applying for U.S. citizenship, who are seeking to fully engage civically. “While this effort may result in relatively few denaturalizations, it shows that the [Trump] administration’s desire to keep immigrants ‘looking over their shoulder’ extends past legalization and even naturalization. If you weren’t born here, this administration is trying to keep you uncomfortable,” Sarah Pierce, a policy analyst at the Migration Policy Institute, said.

While the Justice Department under President Barack Obama pursued denaturalizations, denaturalizations have ramped up under the Trump administration. According to The New York Times, “of the 228 denaturalization cases that the department has filed since 2008, about 40 percent of them were filed since 2017. And over the past three years, denaturalization case referrals have increased by 600 per cent.”

In the past, denaturalization proceedings were rare and brought against those engaged in human rights violations and other extreme cases, such as radical political activity. Notably, denaturalization was brought against former Nazis and other war criminals that had entered the United States under false pretenses. While the increase in denaturalization cases under the Trump administration is significant and suggests a new level of scrutiny of immigration, the number of people who have had their citizenship stripped remains small. Still, people seeking to come to, and make a home for, themselves in the United States should be cognizant of the administration’s focus on denaturalization.