In Schmerber v. California, the U.S. Supreme Court ruled in 1966 that forced blood tests do not violate the Fifth Amendment's protection against self-incrimination. The case arose when Armando Schmerber was arrested for drunk driving and refused to take a sobriety test; however, his blood was drawn while he was at the hospital receiving treatment following an accident related to his arrest. The results of this test were used as evidence in court leading him to argue that it violated his constitutional rights under both Fourth (protection from unreasonable searches) and Fifth Amendments (right against self-incrimination). However, the Supreme Court held that because chemical analysis of blood taken is physical rather than communicative evidence, it does not implicate or trigger protections under the Fifth Amendment’s Self-Incrimination Clause which only protects testimonial communication.

In the dissenting opinion for Schmerber v. California, Justice William O. Douglas argued that the majority's ruling violated the Fifth Amendment's protection against self-incrimination. He contended that forcing a suspect to provide physical evidence, such as a blood sample in this case, was akin to compelling testimony from him or her without consent - an act which he believed should be constitutionally protected under any circumstance. Furthermore, Douglas rejected the distinction made by his colleagues between verbal and physical communication; he insisted that both forms of expression were equally deserving of constitutional safeguards against involuntary incrimination. Lastly, he expressed concern about potential abuses of power by law enforcement if they could forcibly extract bodily substances without violating constitutional rights.