In the 1967 case Bitter v. United States, the Supreme Court examined whether a defendant's constitutional rights were violated when he was not allowed to cross-examine a government witness about his mental history. The defendant, Mr. Bitter, had been convicted of bank robbery and during his trial, one of the key witnesses for the prosecution was an FBI agent who suffered from a mental illness but whose condition was not disclosed to the defense or jury at that time. On appeal, Mr. Bitter argued that this omission denied him his Sixth Amendment right to confront witnesses against him and thus warranted a new trial. The Supreme Court disagreed with Mr.Bitter's argument stating that there is no absolute right of discovery in criminal cases and it is up to judges' discretion on what evidence can be presented in court based on its relevance and reliability.The court also noted that even if such information had been revealed,it would have made little difference as other substantial evidence supported conviction.Hence,the judgment affirmed lower courts' decision denying retrial.

In the dissenting opinion for Bitter v. United States, 1967, Justice Fortas argued that the majority's decision was a departure from established precedent and an unnecessary expansion of federal power. He contended that there was no evidence to suggest that Congress intended to make it a crime for someone who had been convicted of a felony in state court but not yet sentenced or imprisoned to possess firearms under the Federal Firearms Act (FFA). Furthermore, he believed this interpretation would lead to absurd results as it could potentially criminalize individuals who were unaware they were committing an offense due to delays in sentencing or appeals processes. Additionally, Justice Fortas expressed concerns about potential violations of states' rights and principles of federalism by allowing federal prosecution before state proceedings had concluded.