It ISN'T EVERY day that the solicitor general of the United States asks the Supreme Court to invalidate an act of Congress. Normally, it is his job to defend challenged laws. Yet Solicitor General Seth Waxman and Attorney General Janet Reno were correct last week to ask the high court to continue requiring that defendants be read their rights despite a congressional effort to overturn the landmark 1996 case of Miranda v. Arizona.

The law in question was passed in 1968, two years after the high court held that confessions obtained from suspects who had not been advised of their rights were inadmissible in court. Congress specifically intended the law to overturn Miranda and make any voluntary confession admissible. And it enacted the law despite the fact that a constitutional holding by the Supreme Court cannot simply be overturned by an act of Congress.

But despite the clear conflict with a Supreme Court precedent, the 4th Circuit Court of Appeals upheld the law earlier this year in the case of a man named Charles Dickerson. Mr. Dickerson, who is accused of bank robbery, moved to have his confession suppressed on grounds that it was obtained in violation of Miranda -- a contention that appears to be false. But rather than hold that the confession, in fact, complied with Miranda, the court held that, since handing down the famous case, the Supreme Court frequently has used language suggesting that the Miranda warnings are not themselves constitutionally required. Because of this, the 4th Circuit ruled, the law Congress passed can constitutionally supersede Miranda. Mr. Dickerson has asked the high court to review the 4th Circuit's decision.

The 4th Circuit opinion was weak on several grounds -- and especially irksome because the court should never have been considering the issue to start with. Successive Justice Departments have declined to cite the statute out of fears that it may be unconstitutional. Yet the court leaped to rule on this tricky constitutional question when neither prosecutors nor defense lawyers had asked it to do so. The department has thus been forced to go before the Supreme Court and either subvert one of the modern era's most famous decisions or join with a criminal defendant whom it is prosecuting in asking the court to invalidate a congressional enactment.

In this situation, supporting Miranda over the statute is the right call, in spite of the odd posture in which it places the department. Whatever one thinks of the original holding -- which, though majestic in its scope and vision, also had an uncomfortably legislative feel to it -- few decisions have entered the public consciousness quite so thoroughly. Despite the early fears of law enforcement, the Miranda holding has not generally shackled police, though it has surely aided some guilty defendants. For the court to reverse Miranda now, or for the Justice Department to urge it to do so, would be to send the message that even long-settled matters of law are not really stable. That would be genuinely unhealthy. As the department's brief put it, "Miranda has come to play a unique and important role in the nation's conception of our criminal justice system: It promotes public confidence that the criminal justice system is fair." That role continues to warrant respect.