Currently being briefed before the U.S. Supreme Court on the merits is a test of the federal statutory ban, with severe felony penalties, for any marijuana "user" who possess a firearm or even a single round of ammunition. 18 U.S.C. sec. 922(g)(3). The Supreme Court's docket page is here. And here is the amicus brief I coauthored on behalf of the National Rifle Association, FPC Action Foundation, and Independence Institute (where I work). The lead author was NRA's litigation director Joseph Greenlee. As always in a Greenlee brief, the originalist legal history is complete and impeccable.
Below is the Summary of Argument.