Cite as: 575 U. S. ____ (2015) 9 Opinion of the Court clude courts from implying an unexpressed “intent to threaten” requirement in Section 875(c). See Russello v. United States, 464 U. S. 16, 23 (1983) (“[W]here Congress includes particular language in one section of a statute but omits it in another section of the same Act, it is generally presumed that Congress acts intentionally and purposely in the disparate inclusion or exclusion.”). The Government takes this expressio unius est exclusio alterius canon too far. The fact that Congress excluded the requirement of an “intent to extort” from Section 875(c) is strong evidence that Congress did not mean to confine Section 875(c) to crimes of extortion. But that does not suggest that Congress, at the same time, also meant to exclude a requirement that a defendant act with a certain mental state in communicating a threat. The most we can conclude from the language of Section 875(c) and its neighboring provisions is that Congress meant to proscribe a broad class of threats in Section 875(c), but did not identify what mental state, if any, a defendant must have to be convicted. In sum, neither Elonis nor the Government has identified any indication of a particular mental state requirement in the text of Section 875(c). B The fact that the statute does not specify any required mental state, however, does not mean that none exists. We have repeatedly held that “mere omission from a criminal enactment of any mention of criminal intent” should not be read “as dispensing with it.” Morissette v. United States, 342 U. S. 246, 250 (1952). This rule of construction reflects the basic principle that “wrongdoing must be conscious to be criminal.” Id., at 252. As Justice Jackson explained, this principle is “as universal and persistent in mature systems of law as belief in freedom of the human will and a consequent ability and duty of the