In the case of Palermo v. United States (1958), the Supreme Court ruled on issues related to a defendant's right to access government-held evidence before trial, in this instance, statements made by witnesses during an investigation. The court held that only those portions of witness statements which are relevant and material to the defense must be produced for inspection. This decision was based on Rule 16 of Federal Rules of Criminal Procedure which does not require complete disclosure but rather "production upon a showing of cause". In this particular case, Frank Palermo and others were convicted for conspiracy to evade federal wagering taxes. They appealed their convictions arguing they should have been allowed full access to all prior written statements given by prosecution witnesses before cross-examination at trial as per Jencks Act (18 U.S.C.A §3500). However, the Supreme Court upheld their convictions stating that it is up to the discretion of trial judges whether or not such materials need be disclosed.

In the dissenting opinion for Palermo v. United States, Justice Brennan disagreed with the majority's interpretation of Rule 16 of the Federal Rules of Criminal Procedure. He argued that it was not intended to restrict a defendant's access to statements made by government witnesses only to those which could be used at trial under common law rules of evidence. Instead, he believed that any statement relevant to the subject matter of the testimony should be available for cross-examination purposes regardless if they are admissible in court or not. Furthermore, he criticized how this ruling would allow prosecutors too much discretion in determining what constitutes as a 'statement', potentially leading them withhold crucial information from defendants and their counsel during trials.