In the United States v. Ryan case of 1955, the Supreme Court ruled that a grand jury witness could not refuse to answer questions based on the general fear of self-incrimination. The defendant, James J. Ryan, had been subpoenaed by a federal grand jury investigating possible violations of antitrust laws in the milk industry and refused to answer certain questions claiming his Fifth Amendment privilege against self-incrimination. However, he did not specify how these answers might incriminate him but argued that any response could potentially lead to criminal prosecution. The court held that this was insufficient for invoking Fifth Amendment rights as it would allow witnesses to avoid answering merely because they feared potential future consequences rather than having specific reasons for believing their responses may be incriminating.

In the dissenting opinion for United States v. Ryan, Justice Harlan argued that the majority's decision was inconsistent with previous rulings and principles of statutory interpretation. He contended that the court had previously held in a similar case involving an antitrust statute (United States v. Kissel) that a conspiracy does not continue indefinitely just because its effects persist; rather, it ends when there is no further action taken to carry out its objectives. Applying this reasoning to Ryan's case, he suggested that his alleged conspiracy to defraud the U.S government ended once all fraudulent claims were submitted and paid by 1947 - well before the five-year statute of limitations period began in 1951. Justice Harlan also criticized the majority for interpreting "defraud" too broadly under Section 371 of Title 18 which criminalizes conspiracies to defraud US government agencies or departments. He believed such broad interpretation could potentially make any violation of federal regulations into a fraud offense if it somehow interfered with governmental functions. Lastly, he expressed concern over potential abuse where prosecutors might use this expansive definition as leverage during plea negotiations or unfairly charge defendants multiple times for essentially same conduct under different statutes – thus violating double jeopardy protections.