A gun conviction can carry extremely severe immigration consequences for persons that are not United States citizens. INA section 237(a)(2)(C) makes convictions under federal, state, and local laws for firearms offenses deportable. The list of offenses that fall under this provision is very broad. Even very minor firearm convictions, such as negligent discharge of a gun, brandishing a pistol, unlawful transport of a firearm, etc., can all potentially lead to deportation. Many firearms offenses (not all) are considered to be aggravated felonies that can lead to deportability, inadmissibility, and denial of adjustment of status. One such offense that is noteworthy is the possession of a firearm by an illegal alien or an alien in non-immigration status (see 18 USC section 922(g)(5). Also, if a sentence of 1 year or more is imposed on a crime of violence conviction, it is also considered to be an aggravated felony (see INA section 101(a)(43)(F).
Is it ever legal for aliens to possess firearms? In some limited cases, yes. An alien who has been lawfully admitted to the United States under a non-immigration visa who is admitted to the United States for for lawful hunting or sporting purposes, or is in possession of a hunting license or permit lawfully issued in the United States may possess lawful firearms under 18 USC section 922(y)(2)(A). Lawful Permanent Residents (green card holders) can also possess firearms as long as they follow the applicable state, federal, and local laws to do so. Even an alien or green card holder that lawfully possesses or uses a firearm may run into trouble with their immigration status for firearms related violations. It is advisable that an alien or green card holder who wants to possess or use firearms consult with a lawyer, and receive proper training, so he or she specifically understand what the law requires. Again, even a relatively minor gun violation can result in catastrophic immigration consequences.
Deportability for a firearms offense will trigger mandatory detention. This means that a non citizen who is in immigration proceedings for a firearm related conviction will be held in immigration custody while removal proceedings are pending (see INA section 236(c)(1)(B). An immigration judge will be without jurisdiction to set a bond when mandatory detention applies.