In Schacht v. United States, the Supreme Court ruled in favor of Daniel Jay Schacht, who was convicted for wearing a military uniform during a theatrical performance without authorization. The court held that the law under which he was prosecuted - 10 U.S.C § 772(f) - violated his First Amendment rights to freedom of speech because it allowed individuals to wear uniforms if they were portraying the military in a positive light but not when criticizing it. This selective permission constituted viewpoint discrimination and thus infringed upon free speech protections guaranteed by the Constitution. Therefore, Schacht's conviction was overturned on grounds that this aspect of the statute is unconstitutional.

In the dissenting opinion for Schacht v. United States, Justice Harlan argued that the majority's decision was overly broad and could potentially undermine military discipline. He contended that while freedom of speech is a fundamental right, it does not supersede all other considerations in every circumstance. In this case, he believed that maintaining order within the military should take precedence over an individual's right to free expression when wearing a uniform unauthorizedly or improperly as part of a theatrical performance critical of U.S. foreign policy (Vietnam War). Justice Harlan expressed concern about potential disruptions to morale and discipline if service members were allowed to wear their uniforms during political protests without any restrictions whatsoever.