In Palmieri v. Florida (1968), the U.S Supreme Court dealt with a case involving Joseph Palmieri, who was convicted of robbery in a Florida state court and sentenced to life imprisonment. He appealed his conviction on the grounds that he had been denied effective assistance of counsel during his trial because his lawyer did not object to certain evidence being admitted which should have been excluded under Miranda rights rules. The Supreme Court dismissed this claim, stating that it could not be proven that there was any prejudice against him as a result of this alleged failure by his attorney. Furthermore, they found no constitutional error in admitting into evidence statements made by Palmieri after he had received warnings compliant with Miranda vs Arizona requirements from an FBI agent prior to questioning.

In the dissenting opinion for Palmieri v. Florida, Justice William O. Douglas argued that the defendant's Sixth Amendment right to counsel was violated when he was not provided with an attorney during a critical stage of his prosecution - specifically, at a preliminary hearing where important rights were determined and potential defenses could be lost if not raised. He believed this denial constituted reversible error under federal law and disagreed with the majority’s decision to affirm Palmieri’s conviction on grounds that no prejudice resulted from this constitutional violation. Furthermore, Douglas contended that it is impossible to determine whether or not actual harm occurred as a result of such deprivation without speculating about what might have happened had counsel been present – something courts are ill-equipped to do accurately or fairly.