The Supreme Court in Chorley v. United States settled the ongoing dispute over the McNabb/Mallory rule. The McNabb/Mallory rule states that any confession given by a arrestee more than six hours after his/her arrest is inadmissible at trial if the arresting officers have not taken the arrestee before a magistrate within six hours of his/her arrest. This presumes that the presentment may be longer than six hours if the delay is necessary for a non-investigative purpose. For example if the arrest occurs above the Arctic Circle in Alaska and a blizzard prevents the arresting officer from bringing the arrestee before the nearest magistrate within six hours.

As Justice Souter said, speaking for the majority:

In a world without McNabb-Mallory, 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. . . . No one with any smattering of the history of 20th-century dictatorships needs a lecture on the subject, and we understand the need even within our own system to take care against going too far. “[C]ustodial police interrogation, by its very nature, isolates and pressures the individual,” . . . and there is mounting empirical evidence that these pressures can induce a frighteningly high percentage of people to confess to crimes they never committed,

In 1943 the Supreme Court in McNabb v. United States used it’s supervisory power over the Federal Court system to exclude confessions obtained in violation of the presentment rule which required that Federal agents bring an arrestee, without unnecessary delay, before the nearest magistrate. The McNabb rule and statutes on the presentment rule were collected in Rule 5(a) of the Federal Rules of Criminal Procedure in 1946. In Mallory v. United States the Supreme Court held, in 1957, that a confession made seven hours after the arrest was excessive and had to be excluded at trial when the interrogation leading to the confession was held in the same Philadelphia courthouse where the magistrate sat.

However, in 1968, Congress enacted 18 U. S. C. 3501 in response to the Miranda decision. Subdivisions (a) and (b) of Section 3501 attempted to abrogate Miranda by admitting all voluntary statements into evidence. (In 2000 the Supreme Court ruled in Dickerson v, United States that Miranda was mandated by the Constitution and therefore could not be abrogated by an act of Congress.) Subdivision (c) was basically a restatement of the McNabb/Mallory rule. It stated:

“a confession made . . . by . . . a defendant therein, while such person was under arrest . . . , shall not be inadmissible
solely because of delay in bringing such person before a
magistrate judge . . . if such confession is found by the trial judge to have been made voluntarily . . . and if such confession was made . . . within six hours [of arrest]”;

However, some courts, including the Third Circuit Court of Appeals, which heard Chorley applied subdivision (a)’s requirement that all voluntary confessions be admitted without the modifying requirements of subdivision (c) that the confession only be admitted if the arrestee was brought before the magistrate within six hours of his/her arrest.

In Chorley the Supreme Court reaffirmed the McNabb/Mallory settled the dispute between the circuits and reaffirmed the McNabb/Mallory rule allowing voluntary confessions to be admitted if they are made prior to presentment of the arrestee before the magistrate within six hours of the arrest.