Chapter 1- Purpose and Background
Revocation of naturalization is sometimes referred to as “denaturalization.” Unlike most other immigration proceedings that USCIS handles in an administrative setting, revocation of naturalization can only occur in federal court.
A person’s naturalization can be revoked either by civil proceeding or pursuant to a criminal conviction. For civil revocation of naturalization, the United States Attorney’s Office must file the revocation of naturalization actions in Federal District Court.  For criminal revocation of naturalization, the U.S. Attorney’s Office files criminal charges in Federal District Court. 
The government holds a high burden of proof when attempting to revoke a person’s naturalization. For civil revocation of naturalization, the burden of proof is clear, convincing, and unequivocal evidence which does not leave the issue in doubt.  For criminal revocation of naturalization the burden of proof is the same as for every other criminal case, proof beyond a reasonable doubt.
USCIS refers cases for civil revocation of naturalization when there is sufficient evidence to establish that the person is subject to one of the grounds of revocation.
The general grounds for civil revocation of naturalization are:
Illegal procurement of naturalization; or
Concealment of a material fact or willful misrepresentation.
Another ground for revocation of naturalization exists in cases where the person naturalized under the military provisions. In those cases, the person may also be subject to revocation of naturalization if he or she is discharged under other than honorable conditions before serving honorably for five years.
On February 14, 2001, a district court issued a nationwide injunction based on a finding that USCIS has no statutory authority to administratively revoke naturalization.  A person’s naturalization can only be revoked after a final order in a judicial proceeding to revoke his or her naturalization.  During a revocation of naturalization proceeding, all related documentation from the A-file is subject to discovery.
USCIS is authorized to cancel any Certificate of Citizenship or Certificate of Naturalization in cases where USCIS considers that the certificate itself was obtained or created illegally or fraudulently.  Cancellation of a certificate under this provision only cancels the certificate and does not affect the citizenship status of the person in whose name the certificate was issued.
If someone was unlawfully naturalized or misrepresented or concealed facts during the naturalization process, civil or criminal proceedings must be instituted to revoke the naturalization and the status of the person as a citizen. Once the naturalization is revoked, the court also cancels the person’s Certificate of Naturalization.
The main difference between cancellation and revocation proceedings is that cancellation only affects the document, not the person’s underlying status. For this reason, cancellation is only effective against persons who are not citizens, either because they have not complied with the entire naturalization process or because they did not acquire citizenship under law, but who nonetheless have evidence of citizenship which was fraudulently or illegally obtained.
Where USCIS has affirmatively granted naturalization to a person, that person is a citizen unless and until that person’s citizenship is revoked.  Revocation, therefore, is appropriate when:
The person filed an Application for Naturalization (Form N-400);
The person appeared at the naturalization interview;
The naturalization application was approved; and
The person took the Oath of Allegiance for naturalization.
By contrast, a person who illegally obtained a Certificate of Naturalization without going through the naturalization process, and was therefore never naturalized by USCIS, is not a citizen of the United States. While the person has a certificate as evidence of U.S. citizenship, the certificate in and of itself, does not confer the status of citizenship.
In such cases, USCIS can initiate proceedings to cancel the Certificate of Naturalization.  Because the person holding this certificate did not obtain citizenship based on a USCIS process, the person maintains whatever immigration status he or she had.
[^ 3] See Kungys v. United States, 485 U.S. 759, 767 (1988).
[^ 4] See Order Granting Order for Permanent Injunction, Gorbach v. Reno, 2001 WL 34145464 (February 14, 2001) (Entering order pursuant to Gorbach v. Reno, 219 F.3d 1087 (9th Cir. 2000)).