At times, a naturalization case can be reviewed by a federal court when denied or not timely completed by USCIS. Generally speaking, filing in federal court is an extraordinary step taken in rare cases, but at times can be a necessary step to ensuring that the law is correctly followed. 

In most circumstances, USCIS has 120 days to either approve or deny a naturalization application following the initial interview. This deadline is written into the statute and must be followed. If a case has been pending for more than 120 days, applicants may file for review by a federal judge. Although doing so can be an extraordinary step in the process, this law was written to ensure that applications are reviewed and decided by USCIS in a timely manner. These types of cases are frequently referred to as "natz delay" or "naturalization delay" cases.

A federal court may also review a denied naturalization case. If USCIS denies an application, it can be reviewed before a federal judge, similar to an appeal.