The Schneider v. Smith case in 1967 involved the United States Supreme Court ruling on whether a member of the U.S. Coast Guard could be court-martialed for refusing to testify before a grand jury about matters that occurred while he was off duty and not related to his military service. The defendant, Schneider, argued that this violated his Fifth Amendment rights against self-incrimination. However, the Supreme Court ruled in favor of Commandant Smith of the U.S Coast Guard stating that members of America's armed forces do not have absolute immunity from being prosecuted by military courts even for offenses committed outside their line of duty or during personal time. This decision underscored an important principle regarding jurisdictional boundaries between civilian and military law enforcement authorities within American jurisprudence.

In the dissenting opinion for Schneider v. Smith, Justice Harlan argued that the majority had failed to properly consider the unique circumstances and requirements of military life. He contended that while civilian courts should generally avoid interfering in internal military matters, they could do so when a service member's constitutional rights were at stake. However, he believed this was not such a case because Schneider willingly joined the Coast Guard and accepted its rules regarding off-duty employment restrictions. Furthermore, Harlan stated that these regulations were necessary for maintaining discipline and readiness within the ranks - factors vital to national security which civilian courts are ill-equipped to judge. Therefore, he concluded that it was inappropriate for them to overrule decisions made by those with expertise in military affairs unless there was clear evidence of constitutional violations or abuses of power.