When it's an "antique firearm," apparently. Eugene Volokh links to a story (above) in which this fact is relevant. He notes: 18 U.S.C. §§ 921-922, which ban felons from possessing firearms, define[s] "firearm" to exclude any "antique firearm," which is to say "any firearm ... manufactured in or before 1898." I mentioned a few weeks ago a case in which the dispute was over the matter of whether the defendant was in fact a felon. I've seen a few of those. This is the first time I've seen a case in which the prosecution cannot prove beyond a reasonable doubt that the object in the felon's possession was a firearm. In this case, it was "an American double-action revolver that was manufactured between 1880 and 1941." Since the prosecution could not prove beyond a reasonable doubt that the revolver was manufactured after 1898, it could not get a conviction on the charge of being a felon in possession of a firearm. Eugene ends his post with the following: Fortunately for the prosecution, the felon-in-possession statute also bars felons from possessing ammunition, and the defendant was convicted of that.