In the case of McKinley et al. v. United States in 1918, the Supreme Court ruled on issues related to income tax evasion and fraud. The defendants, including a former U.S Congressman Albert Johnson and his business partner William McKinley, were convicted for conspiring to defraud the government by evading taxes through fraudulent means such as falsifying documents and misrepresenting their company's profits. They appealed their convictions arguing that they had been denied due process because some evidence used against them was obtained illegally without proper search warrants or subpoenas. The Supreme Court upheld their convictions stating that while it is true that certain rights must be respected during investigations (such as protection from unreasonable searches), these protections do not apply when individuals voluntarily provide false information with an intent to deceive or defraud. Therefore, any evidence obtained under those circumstances can be used against them in court regardless of how it was acquired. This ruling reinforced the principle that no one is above law - even high-ranking officials like congressmen - and everyone has a responsibility to pay taxes honestly without resorting to deceitful practices.

The dissenting opinion in the case of McKinley et al. v. United States argued that the majority's decision to uphold a conviction for conspiracy to obstruct military recruitment during World War I was an overreach and violation of free speech rights under the First Amendment. The dissenters believed that there was insufficient evidence presented at trial to prove beyond reasonable doubt that defendants had intended or acted with criminal intent, as required by law for such convictions. They also expressed concern about potential misuse of this ruling by authorities seeking to suppress political dissent or unpopular views, arguing it could set a dangerous precedent undermining civil liberties and democratic principles enshrined in the Constitution.