Can your oath be revoked?

Yes, U.S. citizenship obtained by naturalization can be revoked, but only in the narrow circumstances of denaturalization where the citizenship was procured by fraud, illegality, or willful misrepresentation of a material fact. Denaturalization is governed by section 340 of the Immigration and Nationality Act (8 U.S.C. section 1451). The federal government, through the Department of Justice's Office of Immigration Litigation, may file a civil action in federal district court to revoke citizenship if it can prove by clear, unequivocal, and convincing evidence that the certificate was illegally procured, was procured by concealment of a material fact, or was procured by willful misrepresentation.

Common grounds include lying on Form N-400 about prior arrests, criminal convictions, or membership in disqualifying organizations; failing to disclose participation in war crimes, persecution, or human rights abuses; or fraud in the underlying immigration status that made naturalization possible. Denaturalization can also occur in criminal proceedings under 18 U.S.C. section 1425 (procurement of citizenship unlawfully) as part of a criminal sentence. A small but notable category involves denaturalization of former Nazis, war criminals, and other human rights violators who concealed their backgrounds.

The Supreme Court has held in Maslenjak v. United States (2017) that the government must prove the misrepresentation was material to the naturalization decision. Once denaturalized, the person reverts to lawful permanent resident status and may be subject to removal proceedings if independent grounds exist; in some cases the person may even lose status entirely. Voluntary renunciation of U.S. citizenship under 8 U.S.C. section 1481 is a separate matter and is the only way a U.S. citizen can lose citizenship without government action.