In the 1951 case Morissette v. United States, the U.S Supreme Court ruled in favor of defendant Joseph Morissette who had been convicted for converting government property to his own use. The issue at hand was whether criminal intent was a necessary element in statutory crimes where it is not explicitly mentioned by Congress. Morissette, without permission, took spent shell casings from a military bombing range and sold them as scrap metal believing this action to be lawful since they were abandoned property. He was charged under a federal statute that made theft or conversion of government property an offense but did not specify intent as part of its elements. The court held that even though the law does not expressly state so, criminal intent must be present for conviction unless excluded by Congress intentionally and clearly which wasn't done here. It emphasized on traditional principles of common law stating that crime usually combines act with guilty mind (actus reus and mens rea). Therefore, despite committing an unlawful act (actus reus), because Morisette lacked wrongful intention or knowledge (mens rea), he could not be criminally liable.

In the dissenting opinion for Morissette v. United States, Justice Robert H. Jackson disagreed with the majority's decision to overturn Morissette's conviction on grounds of lack of criminal intent. He argued that the court was not in a position to alter or reinterpret federal statutes and should instead defer to Congress' authority in defining crimes and punishments under law. Furthermore, he contended that it is not necessary for an individual to know they are breaking a specific law to be found guilty; rather, if they knowingly commit an act which happens to be illegal (in this case, converting government property), then they can still be held accountable regardless of their awareness or understanding of its illegality.