THE MOST IMPORTANT part of many criminal cases, as every lawyer knows, is the pretrial hearing at which a judge decides what evidence can be presented to the jury. It is then that the prosecution's case is often made or broken - when the judge says a confession or a seized packet of narcotics or a particular witness's testimony may or may not be admitted as evidence. So it was disturbing when the highest court of New York State ruled the other day that these hearings should be conducted in secret - unless there is "an overwhelming reason" to hold them in public. In our view there is "an overwhelming reason" to hold these, and almost all other judicial proceedings, in public.

Unfortunately, the trend toward secrecy in the courts is running strong these days. Some judges have ordered newspapers and other news media not to report what has happened in their courtrooms. Others have ordered lawyers and witnesses, as well as court officials, not to discuss particular cases in public. A few have closed the courtroom doors to the press and the public in specific cases. Thus, while this is the first decision we know of in which a court has said a critical part of the trial process should be conducted in secret in almost all cases, it was a predictable next step.

Nevertheless, it is an unhappy event in the protracted dispute that has become known as the "fair trial-free press" controversy. That is because in comtemplating the constitutionally guaranteed "public trial," the court concludes that only the defendant - not the public - has a substantial stake in what goes on in the courtroom. Defendants, of course, do have a primary interest. The question of their guilt shouldn't be decided on the basis of information obtained by jurors outside the courtroom. But the public, too, has an interest in what goes on in those courtrooms. Its real interest lies not in the confessions or the evidence that the judges are taking such desperate steps to keep secret, but rather in the procedures by which justice is administered. To close off from public view an important part of that process is to deny the public information it needs to judge its own courts.

The Supreme Court has not yet sanctioned the kind of secrecy the New York court is imposing. We hope it won't. The view of the New York court elevates the right to a fair trial far above any other provision of the Bill of Rights, giving it a status that history neither requires nor supports. In addition, this view rests on the assumption that the public has complete confidence in the integrity of all its courts and all its judges, which simply is not the case.

It is strange that the courts should be turning toward secrecy as a solution to their problems at a time when other branches of government are turning away from it. The sunshine laws, popular throughout the country just now, did not come into being in a vacuum. They came about because most elected public officials have come to understand that excessive secrecy in government breeds distrust among the citizens as well as corruption among the decision-makers.The courts shouldn't march in the opposite direction.