In the United States v. Raddatz case of 1979, the Supreme Court examined whether a federal district court judge could use evidence from a magistrate's suppression hearing without personally conducting a new hearing. The defendant, Raddatz, had been convicted based on testimony given at such a hearing by an informant who did not appear in court during his trial. He argued that this violated his Sixth Amendment right to confront witnesses against him and that it was improper for the judge to rely on findings made by someone else (the magistrate). However, the Supreme Court disagreed with Raddatz’s argument and ruled in favor of the government. The majority held that there was no constitutional requirement for de novo determination when reviewing magistrates' recommendations; instead, they found it sufficient if judges review transcripts or other records of prior proceedings before making their decisions.

In the dissenting opinion for United States v. Raddatz, Justice Marshall argued that allowing a magistrate to conduct suppression hearings and then present recommendations to district judges was unconstitutional. He believed this practice violated the defendant's right under the Sixth Amendment to have their case heard by an impartial jury or judge. Additionally, he contended that it undermined Article III of the Constitution which vests judicial power in courts presided over by lifetime-appointed judges rather than magistrates who lack such tenure protections. Furthermore, he expressed concern about potential bias as magistrates are employees of the court system and may feel pressured to rule in favor of government prosecutors. Lastly, Justice Marshall felt that this process could lead defendants feeling like they did not receive a fair trial if their initial hearing was before someone with less authority than a federal judge.