No person under indictment or convicted in any court for a crime punishable by a prison term longer than one year may buy a firearm. Also prohibited are fugitives of the law and unlawful users of any controlled substance. The Gun Control Act also prohibits a person who is subject to a court order restraining him from "harassing, stalking or threatening an intimate partner or child of the intimate partner; or who has been convicted of a misdemeanor crime of domestic violence." All of these criminal charges would show up in a background check before a gun purchase.
The background check also checks for citizenship status. No illegal aliens may purchase firearms. Neither can anyone who has renounced their United States citizenship.
People who have been judged by the court system as being mentally incompetent and those who have been committed to a mental institution may not buy a gun. The background check also identifies military personnel as prohibited from purchasing firearms if they received a dishonorable discharge.
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