For a naturalized citizen, US citizenship can be revoked only through a judicial action, that is, a suit filed in court. Generally, these suits are filed in a federal district court. Typically, the suit is filed in the district court where you live or reside. If you aren't living in the US, the suit can be filed in the United States District Court for the District of Columbia or in the district court for the area where you last resided.
You have to be given "notice" of the suit; the US government has to tell you that a denaturalization action has been filed against you and where the suit was filed. You will be given or "served" a copy of the complaint that's been filed with the court, which tells you why the denaturalization action was filed. Also, the US government must file "affidavit of good cause" detailing exactly why the government is trying to revoke your citizenship.
You have 60 days to file an answer to the government's complaint, where you can challenge the government's claims and raise any defenses against revocation. For example, you may claim that the revocation is based on wrong information, such as that the government is mistaken about a past criminal conviction that it claims you failed to report on your naturalization application.
The government must prove its case against you by evidence that is clear, unequivocal, and convincing and doesn't leave any doubt that your citizenship should be revoked. If it's successful, your certificate of citizenship will be revoked immediately.
Obviously, having your US citizenship revoked is serious. If your citizenship is cancelled, you can be removed or deported from the US. And it's not only you that you have to worry about. In some instances, if your citizenship is revoked, members of your family could lose their citizenship too, if their citizenship depends upon your status of being a naturalized citizen. For example, if you're a naturalized citizen and have a child born outside the US, your child may be a US citizen based upon your naturalized status. In some cases, if your citizenship is revoked, your child's citizenship may be revoked as well.
Because of the serious consequences of denaturalization, you should get the advice of an experienced immigration lawyer if a denaturalization lawsuit is filed against you.