It is possible to sue the United States Citizenship and Immigration Services (USCIS) for delays in your naturalization case, but it is not a common or straightforward process. The USCIS is a government agency and, as such, is generally immune from lawsuits for monetary damages. This means you cannot sue simply because your naturalization case takes longer than you would like.
However, limited circumstances exist in which you may sue USCIS for a delay in your naturalization case.
A violation of constitutional rights
One potential option is to file a lawsuit alleging that USCIS violated your constitutional rights. For example, suppose you can show that the agency is intentionally delaying your naturalization case in a discriminatory manner or that the delay is causing you significant harm. In that case, you may have a chance of bringing a lawsuit against them.
A mandamus action
Another option is to file a mandamus action, a lawsuit asking the court to order a government agency to perform a specific duty required by law. In the context of a naturalization case, this could involve asking the court to order USCIS to process your case promptly.
A significant delay
Federal statute 8 U.S.C. § 1447(b), often referred to as 1447b, creates an obligation that USCIS respond to your naturalization application within 120 days. If the government takes longer than that to respond, you may have standing to sue for the delay.
Suing USCIS is an expensive, complex process that is generally only an option for those who have experienced significant delays or other problems with their naturalization case that you cannot resolve through other means.