THE public airing of additional sexual assault accusations against William Kennedy Smith dramatizes the uneven effects of court-imposed "gag orders" on the participants in a criminal trial. A judicial tool designed to protect defendants from prejudicial publicity now most often operates to prevent defendants and their lawyers from responding to publicity about the prosecution's charges.This prejudicial effect on defendants is likely to be increased by a Supreme Court ruling in June. In that 5-to-4 decision, the Rehnquist Court upheld ethics rules that limit what defense lawyers can say in their clients' behalf even after the prosecution's case has been widely publicized. The new accusations against Mr. Smith, nephew of Sen. Edward Kennedy, were contained in a court document filed by the Palm Beach, Fla., assistant state's attorney who is prosecuting Smith for allegedly raping a Florida woman at the Kennedy Palm Beach estate. The prosecutor, Moira K. Lasch, said she had evidence that Smith had raped a woman in Washington in spring 1988, and had attempted to rape two other women in 1983 and 1988. Ms. Lasch said she plans to introduce the evidence at Smith's trial. Lasch could have filed this evidence under seal, but did not. The charges instantly became worldwide news, undermining the credibility of Smith's prior insistence that he is innocent of the charges in the Palm Beach case. But neither Smith nor his lawyers could respond to these stories, because of a gag order issued by the judge - over their objections. The unfairness of this has nothing to do with Smith's guilt or innocence. As New York University Law School ethics expert Stephen Gillers said on National Public Radio, the prosecutor's actions appeared to be a cynical manipulation of a procedure designed to aid the defendant by giving advance notice of evidence to be relied on at trial. Mr. Gillers suggested Lasch's "dominant motive" was to let potential jurors know about these charges even if the accusations are ultimately not allowed into evidence at Smith's trial. Neatly for the prosecutor, however, the gag order prevents her from responding to obvious questions about her motive. When the free trial/fair press issue emerged in the late 1960s, gag orders were viewed as one option for judges to limit publicity that could jeopardize the defendant's chances for an impartial jury. Judges liked the idea as a way to protect any conviction from reversal on appeal. Lawyers had mixed views, but in general defense attorneys looked on the idea more favorably than prosecutors did. Press groups, on the other hand, viewed gag orders as an unnecessary restriction on the public's access to information since courts had many other ways to protect the legal process, such as thoroughly questioning potential jurors or moving a trial elsewhere. And any number of acquittals in high-profile cases can be cited to support the argument that defendants can get a "fair trial" even after massive publicity. There is still no solid evidence that pretrial publicity makes it impossible to get jurors to decide a case based on court evidence rather than what's in newspapers or on TV. But defense lawyers are more aware of their need to present their clients' case at the same time the public is exposed to the prosecution's charges. Thus, Los Angeles attorney Howard Weitzman, who won an acquittal for automaker John DeLorean despite a videotape showing Mr. DeLorean opening a briefcase full of cocaine, sought out the press before, during, and after trial to explain his entrapment defense. Mr. Weitzman said a criminal defense lawyer would be guilty of malpractice if he did not actively work to clear his client both in the a court of law and the court of public opinion. THE Rehnquist Court has a different view. Ruling in June on a discipline case against a Nevada defense lawyer, the majority upheld a widely adopted ethics rule that forbids lawyers from making comments that would have a "substantial likelihood of materially prejudicing" a pending case. The lawyer, Dominic Gentile, held a news conference the day after his client's well-publicized indictment to insist that the real culprit in the alleged theft was a police detective. Gentile's case was sent back to Nevada to determine whether the ethics rule was too vague, but the legal ruling is a green light for state courts and bar associations to go after defense lawyers for advocating their clients' cause anywhere except the courtroom. Prosecutors face no similar peril because, as the Smith case shows, they can publicize accusations through ostensibly proper court filings. The solution is not to impose gag rules more evenhandedly. In an open society, information about the criminal justice system is desirable and inevitable. Indeed, one of the accusations against Smith had already appeared in The National Enquirer before the court filing. The solution is for judges to do their jobs and make sure courtroom procedures are fair for all - and let others, including defense lawyers and the news media, do their jobs too. Unfortunately, the present Supreme Court seems all too concerned about making prosecutors' and judges' jobs easier, at the expense of uninhibited advocacy by lawyers representing defendants who are entitled to a presumption of innocence until a jury says otherwise.