Held: Section 922(g)(3) is unconstitutional as applied to simple unlawful drug users without individualized dangerousness, but Congress may enact tailored legislation under its Commerce Clause power requiring drug testing or treatment as condition of gun ownership, subject to due process.

The Second Amendment secures to the people a right to keep and bear arms for self-defense. The text does not exempt categories of persons, but from the founding era, there was a practice of disarming individuals who were found to be dangerous to themselves or others, as in cases of felons and the mentally incompetent. The historical 'habitual drunkard' laws cited by the government required a judicial determination that the individual was habitually intoxicated to the point of incapacity. Section 922(g)(3), by contrast, automatically and permanently disarms anyone who uses any controlled substance unlawfully, without any process or finding of individual dangerousness. This is inconsistent with the original understanding of the Second Amendment right as belonging to all 'the people' unless they have forfeited it through a judicial proceeding. Under the Tenth Amendment, the federal government lacks general police power; its authority to regulate firearms must be tied to an enumerated power. The Commerce Clause, as originally understood, does not extend to mere possession of a firearm by an individual for self-defense in the home. Therefore, the statute as applied here is invalid. However, the legitimate government interest in preventing drug users from committing violent acts can be achieved through a licensing system that requires a showing of fitness, including drug testing, and provides for pre-deprivation due process. To that end, Congress may enact a constitutional alternative: a licensing scheme for firearm possession by individuals with a history of unlawful drug use, funded by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) from its existing appropriations, with an annual budget cap of $50 million, a sunset after 5 years, oversight by the Department of Justice Office of Inspector General, and enforcement through criminal penalties for false statements. This approach respects both the Second Amendment and public safety. The Court holds that §922(g)(3) is unconstitutional as applied to individuals who are not adjudicated as posing a danger, but the above alternative would survive constitutional scrutiny if enacted.