612
Opinion of the Court
regulation—as items the ownership of which would have the same quasi-suspect character we attributed to owning hand grenades in Freed. But precisely because guns falling outside those categories traditionally have been widely accepted as lawful possessions, their destructive potential, while perhaps even greater than that of some items we would classify along with narcotics and hand grenades, cannot be said to put gun owners sufficiently on notice of the likelihood of regulation to justify interpreting § 5861(d) as not requiring proof of knowledge of a weapon's characteristics.6
6 The dissent asserts that the question is not whether all guns are deleterious devices, but whether a gun "such as the one possessed by petitioner," post, at 632 (which the dissent characterizes as a "semiautomatic weapon that [is] readily convertible into a machinegun," post, at 624, 633, 640), is such a device. If the dissent intends to suggest that the category of readily convertible semiautomatics provides the benchmark for defining the knowledge requirement for § 5861(d), it is difficult to see how it derives that class of weapons as a standard. As explained above, see n. 5, supra, the Government's argument has nothing to do with this ad hoc category of weapons. And the statute certainly does not suggest that any significance should attach to readily convertible semiautomatics, for that class bears no relation to the definitions in the Act. Indeed, in the absence of any definition, it is not at all clear what the contours of this category would be. The parties assume that virtually all semiautomatics may be converted into automatics, and limiting the class to those "readily" convertible provides no real guidance concerning the required mens rea. In short, every owner of a semiautomatic rifle or handgun would potentially meet such a mens rea test.
But the dissent apparently does not conceive of the mens rea requirement in terms of specific categories of weapons at all, and rather views it as a more fluid concept that does not require delineation of any concrete elements of knowledge that will apply consistently from case to case. The dissent sees no need to define a class of items the knowing possession of which satisfies the mens rea element of the offense, for in the dissent's view the exact content of the knowledge requirement can be left to the jury in each case. As long as the jury concludes that the item in a given case is "sufficiently dangerous to alert [the defendant] to the likelihood of regulation," post, at 637, the knowledge requirement is satisfied. See also post, at 624, 639, 640. But the mens rea requirement under a criminal statute is a question of law, to be determined by the court. Our decisions
Page: Index Previous 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 NextLast modified: October 4, 2007