In the case of Ryan v. United States (1964), the Supreme Court ruled on a matter involving tax evasion and fraud. The defendant, Joseph P. Ryan, was convicted for evading taxes by underreporting his income from 1946 to 1949 while he was president of a labor union in New York City. He appealed this conviction arguing that there were errors made during his trial including improper jury instructions and insufficient evidence supporting his guilt beyond reasonable doubt. The Supreme Court upheld Ryan's conviction stating that there was ample evidence presented at trial showing he had received substantial sums as kickbacks from employers whose workers were members of the union he headed, which he did not report as income on his federal tax returns for those years. Furthermore, it rejected claims about incorrect jury instructions regarding willfulness in tax evasion cases; affirming that "willfulness involves a specific intent which must be proven by independent evidence and cannot be inferred from the mere understatement of income." This ruling clarified what constitutes 'willful' behavior when it comes to tax evasion - an important precedent for future similar cases.

In the dissenting opinion for Ryan v. United States, Justice Harlan argued that the majority's decision to uphold a conviction based on evidence obtained through an unauthorized wiretap was inconsistent with previous Supreme Court rulings and violated Fourth Amendment protections against unreasonable searches and seizures. He contended that there should be no distinction between verbal and written communications in terms of privacy rights, asserting that both forms of communication are equally deserving of constitutional protection. Furthermore, he criticized the majority's reliance on Olmstead v. United States (1928), which allowed warrantless wiretapping by federal agents, as outdated given technological advancements since then had made it easier for government intrusion into private conversations without physical trespassing onto property - something not envisioned when Olmstead was decided.