The nonevidentiary uses of compelled testimony and their prejudicial effects are examined in this article. The background of the fifth amendment privilege within the context of leading Supreme Court rulings concerning the constitutionality of compelled testimony laws is outlined. The Kastigar opinion and its effect on lower court decisions and efforts to resolve the decision's ambiguities are analyzed. The article considers the debate over nonevidentiary use. The author maintains that the Supreme Court's construction of the fifth amendment privilege and immunity legislation prohibits any nonevidentiary use that increases the likelihood of criminal penalties for the witness. He challenges the assumption that the difficulty of proving no such use occurred effectively immunizes the witness from prosecution. Suggested procedural safeguards to address the problems associated with excluding nonevidentiary uses of compelled testimony involve restricted access and prima facie use, declaration of intent to prosecute prior to compulsion, and the standard of proof. 187 notes