In 1966 the nation's highest court, then far more liberal than today, sought to remedy the "inherently coercive" process of police questioning with standard cautions. The court said police must tell suspects they have rights, including the presence of a lawyer during questioning.
"You have the right to remain silent. Anything you say may be used against you in a court of law." Such warnings are now considered basic by civil libertarians.
The ruling flowed from the Fifth Amendment's guarantee that no one "shall be compelled in any criminal case to be a witness against himself." But the court never explicitly said its decision or the police warnings were required by the Fifth Amendment.
But when officers fail to deliver Miranda to suspects, valuable evidence is often uncovered; this led Congress to pass a 1968 law that said federal courts do not have to dismiss confessions made without Miranda warnings.
But the law lay largely dormant for nearly 30 years, until a surprising federal appeals court ruling this year.
The 4th U.S. Circuit Court said alleged band robber Charles Dickerson's incriminating remarks to FBI agents should be admitted as trial evidence against him, even though he may not have received a proper Miranda warning.
Neither Dickerson nor the federal prosecutors who opposed his appeal focused on the 1968 law, known as Section 3501. But Paul Cassell, a lawyer representing the conservative Washington Legal Foundation as a friend of the court, argued that 3501 allowed use of the evidence regardless of any Miranda violation.
The appeals court, by an 8-5 vote, agreed. It ruled that 3501 means that failing to issue Miranda warnings no longer requires automatic exclusion of evidence in federal prosecutions.
Cassell professed his confidence in a recent interview: "I think the Supreme Court should be very receptive to upholding 3501. If so, I'd expect to see states following Congress' lead and moving in a similar direction. The potential for expansion is there."
The American Civil Liberties Union contends the Miranda ruling "was based on constitutional ground" and that the 1968 law is blatantly unconstitutional because Congress enacted it "with the express purpose of returning to the pre-Miranda, case-by-case determination of whether a confession was voluntary."
The Clinton administration previously took the same view, with Attorney General Janet Reno calling 3501 unconstitutional.
The court is expected to say in October whether it will review Dickerson's case.