Section 336(b) of the Immigration and Nationality Act (INA), 8 U.S.C. § 1447(b), describes how courts can intervene if USCIS takes too long to decide a post interview naturalization application. Specifically, if USCIS has not made a decision within 120 days after the applicant’s interview, a district court can step in. While INA section 336(b), 8 U.S.C. § 1447(b), addresses delays, INA section 310(c), 8 U.S.C. § 1421(c), addresses denials.

The law states that if USCIS doesn’t make a decision within 120 days after the applicant’s examination, venue for the lawsuit is in the district court where the applicant lives.

The complaint has to be filed in the federal district court where the applicant lives.

Once the suit is filed, the court has exclusive authority to rule on the naturalization application. It can decide the application or remand to USCIS with instructions. The latter is the more common outcome.

For other types of delays in the naturalization process not related to post-interview decisions, applicants can file mandamus or Administrative Procedure Act (APA) lawsuits. One major difference between a 1447(b) and mandamus lawsuits is that the former can deal with the merits of the application, whereas the latter cannot.