The US Supreme Court handed down three decisions Monday, including United States v. Santos, where the Court held 7-2 that the term "proceeds" in a federal money laundering statute [text] means "profits" and not "receipts." Santos had successfully collaterally attacked his conviction under the statute because the government did not prove that he used profits to promote his illegal lottery business. The Court affirmed a decision by the US Court of Appeals for Seventh Circuit and explained, "The rule of lenity requires ambiguous criminal laws to be interpreted in favor of the defendants subjected to them." Read the Court's opinion per Justice Scalia, along with a concurrence from Justice Stevens, a dissent from Justice Breyer, and a dissent from Justice Alito.

In Cuellar v. United States, the Court held that in a money laundering case, the Government must prove that the purpose of transporting money was to conceal it. Cuellar was charged and convicted with violation of an international money-laundering statute after thousands of dollars were found concealed under the floorboards of his car, which he was driving back to Mexico. The Court reversed a decision by the US Court of Appeals for the Fifth Circuit, ruling that "the statute does not require proof that the defendant attempted to 'legitimize' tainted funds [but] the Government must demonstrate that the defendant did more than merely hide the money during its transport." Justice Thomas delivered the opinion of the court and Justice Alito filed a concurrance.