In the case of Blau v. United States, 1950, petitioner Irving Blau was convicted for refusing to answer questions before a federal grand jury regarding alleged Communist activities on grounds that his answers could incriminate him. The Supreme Court upheld his conviction in an 8-1 decision, ruling that the Fifth Amendment protection against self-incrimination does not apply when there is no reasonable cause to apprehend danger from direct answers given in any ordinary criminal proceeding. The court held that mere conjecture about future prosecutions did not constitute sufficient risk of self-incrimination and thus rejected Blau's claim of privilege under the Fifth Amendment. This case established a precedent requiring individuals to demonstrate specific risks associated with potential self-incrimination rather than relying on general assertions or hypothetical scenarios.

In the dissenting opinion for Blau v. United States, Justice Douglas argued that the majority's decision to uphold Blau's conviction was a violation of his Fifth Amendment rights against self-incrimination. He contended that compelling Blau to produce records from his business under threat of contempt charges effectively forced him into providing evidence against himself in a criminal case, which is expressly prohibited by the Constitution. Furthermore, he disagreed with the majority's assertion that this protection only applies when an individual is asked to provide oral testimony; instead, he believed it should extend to any form of communication or record-keeping. In essence, Justice Douglas felt strongly that individuals should not be legally obligated to assist in their own prosecution and saw this ruling as setting a dangerous precedent for future cases involving similar circumstances.