In the case of Lykes v. United States (1951), the Supreme Court ruled on a matter involving income tax evasion. The defendant, W.J. Lykes Jr., was charged with evading taxes by falsely declaring his income for 1940 and 1941 to be lower than it actually was. He argued that he had not committed fraud because he believed in good faith that his declared income was correct at the time of filing, even though it later turned out to be incorrect due to an error made by his accountant. The court held that a taxpayer could still be found guilty of willful evasion if they knowingly understate their taxable income, regardless of whether or not they believe in good faith that their declaration is accurate based on information provided by others such as accountants or lawyers. This ruling established an important precedent regarding intent and knowledge in cases involving tax evasion: taxpayers cannot evade liability simply through ignorance or reliance on professional advice if they are aware at some level that their declarations are false.

In the dissenting opinion for Lykes v. United States, Justice Douglas argued that the majority's decision to uphold a conviction under the False Claims Act was incorrect because it failed to consider whether there was an actual intent to defraud on part of the defendants. He emphasized that in order for a claimant to be found guilty under this act, they must have knowingly presented false claims with fraudulent intentions. In this case, he believed that while errors may have been made by Lykes Bros., these were due more likely due to confusion over complex wartime regulations rather than any deliberate attempt at fraudulence. Furthermore, he pointed out inconsistencies in how similar cases had been handled previously and expressed concern about potential misuse of power by government agencies if such broad interpretations of law were allowed without clear evidence of intentional wrongdoing.