(CN) - Confessions obtained by federal authorities can be suppressed if they were obtained before a suspect's initial court appearance, the U.S. Supreme Court ruled Monday on a 5-4 vote.
The ruling is in step with precedent, which holds that even voluntary confessions are inadmissible if given during an unreasonable delay in the defendant's appearance before a judge.
In Mallory v. U.S., the high court held that a confession given seven hours after arrest inadmissible for "unnecessary delay."
This standard held fast until 1968, when Congress enacted a law meant to override Miranda v. Arizona. The law provides says a confession can be admissible if it is voluntarily given within six hours of the arrest.
The high court was asked to determine whether Congress meant to eliminate or narrow the so-called McNabb-Mallory rule, which renders confessions inadmissible if they violate the "prompt presentment" requirement.
The majority held that the law merely protected voluntary confessions given within six hours of a suspect's arrest.
The government had argued that the law makes all voluntary confessions admissible, thereby eliminating the McNabb-Mallory rule. The Supreme Court ruled that such an interpretation rendered a portion of the federal law "nonsensical and superfluous" and gives the government too much leverage over suspects.
"Federal agents would be free to question suspects for extended periods before bringing them out in the open, and we have always known what custodial secrecy leads to," Justice Souter wrote.
FBI agents in the underlying case drew a confession from prisoner Johnnie Corley in the 29.5 hours he was in custody before seeing a judge. Corley had been accused of robbing a credit union in Norristown, Pa.
The 3rd Circuit ruled that Corley's confession could be used against him, because he had offered it voluntarily despite the delay.
The high court vacated that ruling and remanded, ordering the lower courts to determine whether the confession was given during the first six hours after arrest. If not, the courts must throw out the confession based on an "unreasonable or unnecessary" delay, Souter said.
In dissent, Justice Alito said all voluntary confessions should be admitted, regardless of any delays. He added that Miranda warnings protect against coerced confessions.
Chief Justice Roberts and Justices Scalia and Thomas joined Alito's dissent.
Read the Top 8
Sign up for the Top 8, a roundup of the day's top stories delivered directly to your inbox Monday through Friday.