The prohibition is written around what the seller knows, not around what is objectively true. No person may sell or otherwise dispose of any firearm or ammunition to any person knowing, or having reasonable cause to believe, that the recipient falls into one of the listed categories — and the list applies including as a juvenile. That formulation is what turns the counter into a place of judgment rather than pure procedure: a check that returns Proceed does not cure a reasonable cause to believe that arose in conversation.

The categories divide into three groups by what they turn on, and the concept blocks below set them out so they can be scanned rather than parsed. The first group turns on a criminal status: a person under indictment for, or convicted in any court of, a crime punishable by imprisonment for a term exceeding one year — subject to the exceptions in §§ 478.143 and 478.144 — and a fugitive from justice. The second turns on a personal condition or standing: an unlawful user of, or person addicted to, any controlled substance as the Controlled Substances Act defines it; a person adjudicated as a mental defective or committed to a mental institution at 16 years of age or older; certain aliens; a person discharged from the Armed Forces under dishonorable conditions; and a person who, having been a United States citizen, has renounced that citizenship.

The third group turns on findings made about the person rather than a status they hold, and its conditions are the ones most often skipped. A person subject to a court order restraining them from harassing, stalking or threatening an intimate partner or that partner’s child qualifies only where the order was issued after a hearing of which they had actual notice and at which they had the opportunity to participate, and which either includes a finding that they represent a credible threat to physical safety or explicitly prohibits the use, attempted use, or threatened use of physical force. A restraining order alone does not do it. Alongside that sit a person convicted of a misdemeanor crime of domestic violence, and a person who intends to sell or otherwise dispose of the firearm or ammunition in furtherance of a felony or a federal crime of terrorism.