In the case of Waldemar Ratzlaf and Loretta Ratzlaf v. United States, 1993, the Supreme Court ruled in favor of the defendants who had been charged with violating federal law by "structuring" bank transactions to avoid reporting requirements for cash deposits over $10,000. The court held that to convict someone under this law, it must be proven that they knew their actions were illegal - not just that they intentionally structured their transactions to avoid triggering a report. In other words, ignorance of this specific law could be used as a defense against prosecution. This decision was based on an interpretation of legislative intent; however, Congress later amended the statute to clarify its intention: structuring is illegal even if one does not know it's against the law.

In the dissenting opinion for Waldemar Ratzlaf and Loretta Ratzlaf v. United States, Justice Blackmun argued that the majority's interpretation of 31 U.S.C. §5322(a) was incorrect and inconsistent with Congress' intent to penalize those who intentionally evade federal currency reporting requirements by structuring transactions in a certain way. He contended that it is not necessary for the government to prove that defendants knew their actions were illegal, but rather they only need to demonstrate an intention to avoid triggering banks’ reporting obligations. The dissent also criticized the majority’s reliance on legislative history as misguided because there was no clear evidence indicating Congress intended such a high burden of proof when prosecuting these offenses under this statute.