Mallory v. United States

In 1943, the Supreme Court held, in McNabb v. United States that a confession--even one given voluntarily--obtained while a criminal suspect is unlawfully detained (i.e., held for a prolonged period without being formally charged) is inadmissible in federal court. In Mallory, this rule was reaffirmed. Writing for a unanimous Court, Justice Frankfurter, the author of the McNabb opinion, stated:

The scheme for initiating a federal prosecution is plainly defined. The police may not arrest upon mere suspicion but only on "probable cause." The next step in the proceeding is to arraign the arrested person before a judicial officer as quickly as possible so that he may be advised of his rights and so that the issue of probable cause may be promptly determined. The arrested person may, of course, be "booked" by the police. But he is not to be taken to police headquarters in order to carry out a process of inquiry that lends itself . . . to eliciting damaging statements to support the arrest and ultimately his guilt.

The Supreme Court can only overturn criminal convictions in state courts if they violate the due process rights guaranteed by the Fourteenth Amendment. The Court can, however, formulate rules of evidence that go beyond due process when exercising its power to supervise criminal trials in federal court. The so-called McNabb-Mallory rule imposed strict limitations on the admissibility of confessions in federal criminal trials, and many feared that the Court might succeed in making the rule applicable to the states through the Fourteenth Amendment. In 1968, Congress severely limited the reach of the McNabb-Mallory rule with legislation that spelled out the circumstances under which a voluntary confession can be admitted in federal court.

The Supreme Court, in the meantime, approached the problem of coerced confessions by focusing on the issue of the Fifth Amendment privilege against self-incrimination and the Sixth Amendment right to counsel. These efforts culminated in the landmark Miranda v. Arizona (1966) case, which required that criminal suspects be given "Miranda warnings" outlining their Fifth and Sixth Amendment rights before they are even taken into custody.