Cite as: 575 U. S. ____ (2015) 9 THOMAS, J., dissenting ing that he acted in self-defense has not been penalized under a negligence standard merely because he does not know that the jury will reject his argument that his “belief in the necessity of using force to prevent harm to himself [was] a reasonable one.” See 2 W. LaFave, Substantive Criminal Law §10.4(c), p. 147 (2d ed. 2003). The Court apparently does not believe that our tradi­ tional approach to the federal obscenity statute involved a negligence standard. It asserts that Hamling “approved a state court’s conclusion that requiring a defendant to know the character of the material incorporated a ‘vital element of scienter’ so that ‘not innocent but calculated purveyance of filth . . . is exorcised.’ ” Ante, at 15 (quoting Hamling, 418 U. S., at 122 (in turn quoting Mishkin v. New York, 383 U. S. 502, 510 (1966)). According to the Court, the mental state approved in Hamling thus “turns on whether a defendant knew the character of what was sent, not simply its contents and context.” Ante, at 15. It is unclear what the Court means by its distinction be­ tween “character” and “contents and context.” “Character” cannot mean legal obscenity, as Hamling rejected the argument that a defendant must have “awareness of the obscene character of the material.” 418 U. S., at 120 (internal quotation marks omitted). Moreover, this dis­ cussion was not part of Hamling’s holding, which was primarily a reaffirmation of Rosen. See 418 U. S., at 120– 121; see also Posters ’N’ Things, 511 U. S., at 524–525 (characterizing Hamling as holding that a ��statute prohib­ iting mailing of obscene materials does not require proof that [the] defendant knew the materials at issue met the legal definition of ‘obscenity’ ”). The majority’s treatment of Rosen is even less persua­ sive. To shore up its position, it asserts that the critical portion of Rosen rejected an “ ‘ignorance of the law’ de­ fense,” and claims that “no such contention is at issue here.” Ante, at 15. But the thrust of Elonis’ challenge is