Hunter Biden, the troubled son of President Joe Biden, was convicted this week of three charges related to illegally purchasing a gun while suffering from drug addiction. It is fair to ask whether prosecutors should have brought these charges in the first place; Reason’s Jacob Sullum described the violated law in question as “widely flouted, haphazardly enforced, and constitutionally dubious.” Republican Rep. Thomas Massie (R–Ky.) wrote on X: “Hunter might deserve to be in jail for something, but purchasing a gun is not it. There are millions of marijuana users who own guns in this country, an…