10 ELONIS v. UNITED STATES Opinion of the Court normal individual to choose between good and evil.” Id., at 250. The “central thought” is that a defendant must be “blameworthy in mind” before he can be found guilty, a concept courts have expressed over time through various terms such as mens rea, scienter, malice aforethought, guilty knowledge, and the like. Id., at 252; 1 W. LaFave, Substantive Criminal Law §5.1, pp. 332–333 (2d ed. 2003). Although there are exceptions, the “general rule” is that a guilty mind is “a necessary element in the indictment and proof of every crime.” United States v. Balint, 258 U. S. 250, 251 (1922). We therefore generally “interpret[ ] criminal statutes to include broadly applicable scienter requirements, even where the statute by its terms does not contain them.” United States v. X-Citement Video, Inc., 513 U. S. 64, 70 (1994). This is not to say that a defendant must know that his conduct is illegal before he may be found guilty. The familiar maxim “ignorance of the law is no excuse” typically holds true. Instead, our cases have explained that a defendant generally must “know the facts that make his conduct fit the definition of the offense,” Staples v. United States, 511 U. S. 600, 608, n. 3 (1994), even if he does not know that those facts give rise to a crime. Morissette, for example, involved an individual who had taken spent shell casings from a Government bombing range, believing them to have been abandoned. During his trial for “knowingly convert[ing]” property of the United States, the judge instructed the jury that the only question was whether the defendant had knowingly taken the property without authorization. 342 U. S., at 248–249. This Court reversed the defendant’s conviction, ruling that he had to know not only that he was taking the casings, but also that someone else still had property rights in them. He could not be found liable “if he truly believed [the casings] to be abandoned.” Id., at 271; see id., at 276. By the same token, in Liparota v. United States, we