In the United States v. Monia et al., 1942, the Supreme Court ruled that defendants must be aware of their right to refuse self-incrimination under the Fifth Amendment during a non-judicial investigation. The case involved two employees who were subpoenaed by a grand jury and questioned about potential violations of federal law in their workplace. They answered all questions without being informed they could decline to answer on grounds it might incriminate them. Later, they were indicted based on those answers and convicted for perjury for lying during questioning. On appeal, the Supreme Court reversed these convictions stating that unless individuals are clearly made aware of their constitutional privilege against self-incrimination, any statements made cannot be used as evidence against them in criminal proceedings.

In the dissenting opinion for United States v. Monia et al., Justice Frank Murphy argued that the majority's interpretation of Section 2(c) of the Criminal Code was too broad and could potentially infringe upon an individual's Fifth Amendment rights against self-incrimination. He contended that a person should not be penalized for refusing to answer questions in any proceeding, civil or criminal, where their answers could incriminate them in future criminal proceedings. According to him, this protection extends beyond just courtrooms and includes all governmental inquiries where responses might tend to incriminate. Furthermore, he disagreed with the majority’s view that immunity must be expressly invoked by individuals; instead he believed it is automatically conferred when one is compelled to testify about matters which may incriminate him/her.