mcnabb-mallory rule n[after McNabb v. United States , 318 U.S. 332 (1943) and Mallory v. United States , 354 U.S. 449 (1957), U.S. Supreme Court cases that established the rule]
: a doctrine in criminal procedure: an arrestee must be brought before a magistrate without unnecessary delay in order for a confession made during detention to be admissible NOTE: In practice, the rule is not absolute. Under the U.S. Code, a delay of more than six hours in bringing an arrestee before a magistrate will not render a confession inadmissible if the delay was reasonable in light of distance and transportation.
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.