In Delli Paoli v. United States, the Supreme Court examined whether a defendant's rights were violated when his confession was used in court, even though it implicated another defendant who did not have an opportunity to cross-examine him. The case involved two men charged with transporting stolen goods across state lines. One of them confessed and implicated the other, but he later refused to testify at trial. Despite this refusal, his confession was admitted into evidence against both defendants. The majority ruled that there had been no violation of constitutional rights because instructions given by the judge should have ensured that jurors only considered the confession as evidence against its author and not against his co-defendant. However, four justices dissented from this view arguing that such instructions are insufficient protection for a defendant’s right to confront witnesses under Sixth Amendment since juries cannot be relied upon to compartmentalize evidence in such manner.

In the dissenting opinion for Delli Paoli v. United States, Justice Frankfurter argued that the majority's decision violated the defendant's Sixth Amendment rights to a fair trial and confrontation of witnesses against him. He contended that it was impossible for jurors to disregard testimony about a co-defendant’s confession implicating another defendant when considering their verdict, despite being instructed by judges to do so. This "mental gymnastics" is beyond what can be expected from average individuals serving as jurors, he said. Furthermore, he believed this practice undermined public confidence in the fairness of criminal trials and could lead to wrongful convictions based on unreliable evidence or hearsay confessions made outside court without cross-examination opportunities for defendants implicated by such statements.