Department of Treasury, Bureau of Alcohol, Tobacco and Firearms v. Galioto

Generally, convicted felons

Felony

A felony is a serious crime in the common law countries. The term originates from English common law where felonies were originally crimes which involved the confiscation of a convicted person's land and goods; other crimes were called misdemeanors...

and mental patients are prohibited from purchasing firearm

Firearm

A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

s in the US. 18 USC 925 allowed some felons to appeal to the BATF

Bureau of Alcohol, Tobacco, Firearms and Explosives

The Bureau of Alcohol, Tobacco, Firearms and Explosives is a federal law enforcement organization within the United States Department of Justice...

to restore their rights to purchase firearms. At that time, prior mental patients did not have a similar route to restore their right to purchase firearms. The appellee argued that this was unreasonable and discriminatory.

Between the time that the court agreed to hear BATF v. Galioto, and the time that the case was heard, PL 99-308 was signed into law, allowing former mental patients to appeal to restore their rights to purchase firearms, rendering the case moot

Mootness

In American law, a matter is moot if further legal proceedings with regard to it can have no effect, or events have placed it beyond the reach of the law...

See also