Originally Posted by Dr Big Bird PhD
...Say that the defendant can prove without a doubt that at the time of purchasing/filling out his 4473, he had never engaged in a federally controlled substance, yet since then he engaged in SD homicide and had smoked weed 2 weeks prior?...
It may be that someone is not an unlawful user of a controlled substance when he buys a gun. At some later date, if he becomes an unlawful user of a controlled substance his continued possession of a gun, even if originally lawfully acquired, would be a crime under federal law. Whether someone is an unlawful user of a controlled substance depends on the exact circumstances and could finally be a question for a judge or jury.