The United States v. Dionisio case in 1972 revolved around the issue of whether grand jury subpoenas requiring voice exemplars from individuals violated their Fourth or Fifth Amendment rights. The Supreme Court ruled that it did not, as a person's voice is exposed to the public and thus does not have an expectation of privacy under the Fourth Amendment. Additionally, providing a voice sample was deemed non-testimonial and therefore did not violate self-incrimination protections under the Fifth Amendment. This decision upheld lower court rulings which had denied motions to quash such subpoenas on these grounds.

In the dissenting opinion for United States v. Dionisio, Justice William O. Douglas argued that compelling a person to provide voice exemplars violated their Fifth Amendment rights against self-incrimination. He contended that the majority's decision expanded government power and diminished individual liberties by allowing law enforcement to compel individuals to produce physical evidence without any constitutional safeguards in place. Furthermore, he disagreed with the majority's view that voice exemplars were not testimonial or communicative in nature - asserting instead they could reveal personal details about an individual (such as health condition) beyond mere identification purposes which should be protected under privacy rights of Fourth Amendment too.