In the 1948 case Upshaw v. United States, the U.S. Supreme Court ruled that a confession obtained from a suspect who had been detained illegally could not be used as evidence in court. The defendant, Willie Upshaw, was arrested without a warrant and held for over thirty hours before being arraigned - significantly longer than what is typically allowed by law enforcement procedures. During this time period, he confessed to committing robbery which led to his conviction in lower courts. However, on appeal at the Supreme Court level it was determined that his extended detention violated Rule 5(a) of Federal Rules of Criminal Procedure requiring prompt presentation of an arrestee before a magistrate judge; thus making any subsequent confessions or admissions made during this illegal detention inadmissible under McNabb v United States (1943). This ruling reinforced protections against coerced confessions and unlawful detainment.

In the dissenting opinion for Upshaw v. United States, Justice Reed argued that the majority's decision to overturn Upshaw's conviction on grounds of a delay in arraignment was misguided. He contended that there was no evidence to suggest that this delay had resulted in any prejudice against Upshaw or influenced his confession of guilt. Furthermore, he pointed out that while Rule 5(a) of Federal Rules of Criminal Procedure does require prompt arraignment, it does not specify a time limit nor stipulate automatic reversal upon violation. Therefore, he believed such violations should be handled on a case-by-case basis considering whether they have caused actual harm to the defendant’s rights rather than adopting an absolute rule which might result in freeing guilty defendants without just cause.