THERE IS LITTLE that is extraordinary about the Supreme Court's decision this week in the Robert Williams case other than the outburst of temper on the part of the Chief Justice. The case did involve a particularly vicious murder - the killing on Christmas Eve, 1968, of a 10-year-old girl by an escaped mental patient. And the decision was close - his conviction was overturned by a vote of 5 to 4 when a majority of the justices ruled he had been denied effective assistance of counsel. But no new legal ground was broken, and the outcome turned on how established constitutional rules should be applied to a particular set of facts. However, the Chief Justice, disagreeing with both the rules and their application, used the occasion to flay his colleagues and to assert that any organized society ought to find their decision "intolerable."

The question that gave rise to this outburst is a basic one. Why should the conviction of an obviously guilty man be set aside because the police failed to follow the rules? And the answer is also basic. Rules, by their very nature, protect the guilty as well as the innocent, and, if rights are to have any meaning, the rules that embody them must be applied in difficult as well as easy cases. The principal rule involved in this case gives suspects the right to have a lawyer present when they are questioned by police.It grew out of a long series of cases in which confessions were extracted from suspects, many of whom did not know that they had a constitutional right to refuse to answer questions. Those cases led a majority of the Court, some years ago, to establish the so-called "exclusionary doctrine," which bars from use at trial evidence seized in violation of the rules. The purpose is to discourage illegal police actions and to ensure that government, as well as private citizens, follows the rules and obeys the law.

In the case decided by the Court this week, the facts made the decision close. Robert Williams had given two detectives the information they sought during a 160-mile auto trip from Davenport to Des Moines, Iowa. The question was whether the detectives had used the period when he was without the help of a lawyer to persuade him to talk despite his lawyer's advice. Before the case reached the U.S. Supreme Court, the Iowa Supreme Court had split, 5 to 4, against the defendant and the Sixth Circuit Court of Appeals had split, 2 to 1 for him.

The Supreme Court also split, 5 to 4, on whether Mr. Williams had been questioned or just talked to and whether he had waived his right to counsel. That is not surprising. Cases of this kind often produce sharp divisions among the justices. What is surprising is the Chief Justice's denunciation of those who disagree with him. Indeed, he appears to be the only justice who favored the upholding of this conviction outright. The three other dissenters voted to send the case back to a lower court for a determination of whether Robert Williams had talked to the detectives voluntarily.

The Chief Justice has repeatedly made it clear that he believes the exclusionary rules are wrong and should be overturned. In fact, the court has overturned some of them. But Justice Powell, who has sided with the Chief Justice in some of these cases, went the other way. Having lost the vote, the Chief Justice wrote so harsh an attack on his colleagues that it provoked separate opinions from Justices Powell, Marshall and Stevens defending the majority opinion of Justice Stewart.

In our view, Justice Stewart's opinion needs no defense. It is terrible when police bungling produces a result such as that in the Williams case. But Mr. Williams is not yet free; he can be tried again. And the complaint of the Chief Justice that the results is "intolerable" seems to us to stand values on their head. What would be truly intolerable is a legal system that permitted police deliberately to violate the constitutional rights of anyone anytime they want to.