Federal law 8 U.S.C. § 922[g](3) states (g) It shall be unlawful for any person— (3) who is an unlawful user of or addicted to any controlled substance (as defined in section 102 of the Controlled Substances Act (21 U.S.C. 802)) to own or purchase a gun.
It is recommended that the Obama administration require all gun owners and purchasers to commit to a drug test to ensure 922[g](3) is enforced.