In the 1973 case Plummer v. City of Columbus, the U.S Supreme Court ruled in favor of a black police officer who had been dismissed from his job for using racially derogatory language towards white officers. The court held that this dismissal violated his First Amendment rights to freedom of speech. The city argued that it was necessary to maintain discipline and morale within the force but failed to provide any evidence supporting their claim. Therefore, without substantial proof showing disruption or impairment caused by such behavior, an employee's right to free speech cannot be curtailed merely on speculative grounds about its potential impact on workplace efficiency or harmony.

In the dissenting opinion for Plummer v. City of Columbus, Justice Rehnquist argued that the majority's decision to overturn a local ordinance on vagueness grounds was an overreach of judicial power. He contended that the court should defer to local authorities in matters concerning public order and safety unless there is clear evidence of constitutional violation. The justice believed that it was not within their purview to decide whether or not this law served its intended purpose effectively or wisely; rather, they were only tasked with determining if it violated any constitutional rights. In his view, since no such violation could be proven beyond reasonable doubt, he felt the court had no basis for striking down this legislation.