In the United States v. Ryan case of 1970, the Supreme Court ruled that a grand jury subpoena cannot be challenged on grounds of insufficient evidence prior to its issuance. The defendant, James Patrick Ryan, was under investigation for possible antitrust violations and received a subpoena to produce certain documents before a grand jury. He filed a motion to quash the subpoena arguing that there wasn't enough evidence against him for probable cause. However, his argument was rejected by both lower courts and eventually by the Supreme Court as well in an 8-1 decision favoring government's right to investigate potential crimes without having established probable cause beforehand.

In the dissenting opinion for United States v. Ryan, Justice Black argued that the majority's decision was a departure from established precedent regarding immunity statutes. He contended that these laws were designed to protect individuals from being compelled to incriminate themselves and should not be used as tools by prosecutors to force testimony. According to him, this interpretation of the law could potentially lead to abuses of power and violations of individual rights. Furthermore, he disagreed with the majority's view that an individual must claim their privilege against self-incrimination in front of a grand jury before they can challenge an immunity order in court. This requirement would place undue burden on individuals who may not have legal representation or understand their rights fully at such proceedings.