AS the O.J. Simpson trial grinds into its ninth month of legal tedium and grandstanding, polls show it has eroded public confidence in the judicial system. Critics often blame Judge Lance Ito, followed by a laundry list of flaws in the current system. But more and more, frustrated legal pundits are turning on the only silent witness in the court: the camera. In high-profile trials - from Susan Smith's murder case in South Carolina to Polly Klaas's kidnapping in California to the Texas trial of pop singer Selena's accused murderer - judges are banning cameras, hoping to avoid a Simpson-like circus atmosphere. An NBC/Wall Street Journal poll taken in June found that 55 percent of Americans say that criminal court trials should not be broadcast. Ironically, the ratings show large numbers of Americans are tuning in to the Simpson trial. ''The camera has turned this into the longest-running entertainment special in America,'' says Don Hewitt, producer of CBS's ''60 Minutes,'' who recently stunned many of his colleagues by criticizing Judge Ito for allowing the trial to be televised in the first place. Over the past 20 years, the controversy surrounding cameras in the courts had pretty much died down. Forty-seven states now allow them in one form or another. In many jurisdictions they have become as much a part of the process as the scribbling print reporter. But the Simpson trial has refueled opponents and re-opened the debate. ''I'm concerned all the time about [a backlash]. I was concerned long before this trial,'' says Steven Brill, the founder and head of Court TV, which since 1991 has broadcast more than 380 trials. ''I always felt the higher our visibility, the more people will think and rethink the issues. This is something that is very new to an old system that I cherish, too.'' Opponents blame the live, televised images of the Simpson trial for the daily media feeding frenzy, the lawyers' questionable antics, and the creation of a new brand of celebrity-hungry juror and witness. In short, they believe it has made a mockery of the judicial system. ''Nobody is watching that to learn how a trial works,'' Mr. Hewitt says. ''They're being entertained.'' But supporters of cameras in courts claim the critics confuse the neutral, televised broadcasts with the lurid sensationalism and second-rate reporting that have accompanied almost every high-profile celebrity trial this century, most of which were not televised. ''Go back to the Sam Sheppard trial,'' says Peter Herford, a professor of journalism at Columbia University here, referring to the notorious 1954 murder case. ''It was one of the biggest circuses of all time. It makes O.J. look like peanuts.'' Advocates also argue that live coverage gives Americans vital access to their own judicial system and a first-hand understanding of how it works, flaws and all. They say the broadcast coverage forces traditional court reporters to be more accurate and responsible. And they point to dozens of studies done over the past 20 years, almost all of which have found the presence of the camera has had a negligible impact. ''The effect of cameras in the courts has been virtually nil,'' says Professor Herford, arguing that the broadcast press has a critical social role to play. ''We're a nation of laws. It's the way we've chosen to live, and it all gets played out in the courts. That's where the big issues of our times get decided.'' The Constitution guarantees the right to a speedy and public trial. Advocates of cameras in the courts argue that the devices simply extend the cavernous public galleries that once were filled to capacity for every high-profile trial. But opponents argue there is a vast difference between a packed courtroom and a television audience of millions. And that difference, they say, can make or break a case. At the trial of Susan Smith, the South Carolina woman who confessed to drowning her two young sons, Judge William Howard banned cameras after pretrial testimony was complete. When issuing his ruling, he said there was ''an absolute likelihood that broadcast coverage in the courtroom would interfere with the due process of this trial.'' Smith's lawyer, David Bruck, said he opposed broadcast coverage for very specific reasons. Smith had been sexually abused throughout her life. Her defense required many of the men involved to testify about those humiliating and embarrassing incidents. ''It was for the sake of the accuracy and integrity of the witnesses' testimony,'' Mr. Bruck says. ''We just thought it was a lot more likely that witnesses would be as courageous as they needed to be, without having to be turned into [Simpson trial witness] Kato Kaelin.'' Critics of cameras in the courts point to the potential intimidation, embarrassment, and harassment of witnesses and jurors as a prime reason for their opposition. They also argue the presence of the camera alters the behavior of the lawyers, the witnesses, and the judges. 'ONCE the motion was granted and the cameras were unplugged, I felt like someone had pumped air back into the room,'' Bruck says. ''I had no idea until the cameras were gone of the effect they were having on everyone.'' While Bruck may have felt what he calls ''a sense of dread'' in the camera's presence, the empirical evidence offers a different picture. Court TV, which depends on cameras in the courts for its survival, collected all of the 41 studies done by states with cameras in the courts since 1974. Overwhelmingly, the studies concluded that the presence of cameras did not impede the process or negatively affect the participants. Of the 24 studies that specifically focused on the effect of the camera on judges and attorneys, 23 found the camera did not alter their behavior. Of the 25 studies that looked specifically at the impact on jurors and witnesses, 24 concluded the camera did not present a significant problem. Some critics blame the length of the Simpson trial on the presence of the cameras. They point to the extraordinary number of sidebars, where the judge and lawyers wrangle outside of the presence of the jury and, critics contend, away from the all-pervading presence of the media. But supporters counter that there have been plenty of other high-profile cases that were not televised that lasted even longer. For instance, the Hillside strangler case lasted 23 months and Charles Manson's murder trial took nine months. The Simpson case was also not the first high-profile trial to attract a substantial number of viewers. In January 1994, the Times Mirror Center for the People and the Press found that almost two-thirds of Americans watched all or parts of the case against Lorena Bobbit, who was accused of sexually mutilating her husband. Fifty-three percent tuned in regularly to Eric and Lyle Menendez's trial for murdering their parents. While the study revealed that most viewers tuned in because of the ''nature of the crimes,'' it also found that more than two-thirds of Court TV's regular viewers came away with a better understanding of legal process and nearly 50 percent had a better impression of the fairness of the judicial system as a result. The Simpson trial appears to be having the opposite effect. In the NBC/Wall Street Journal poll done in June, 51 percent of those polled said the Simpson trial had ''decreased their confidence'' in the judicial system. ''I think it's certainly going to harm the reputations of lawyers and even the justice system itself,'' says Arthur Unger of Television Quarterly, the journal of the National Academy of Television Arts and Sciences. ''I was very much for [cameras in the court] at the beginning of the trial. Now, having spent a year watching it, I'm not so sure.'' The differences between supporters and opponents are also not so clear-cut. For instance, Bruck now says broadcast coverage of the Smith trial would have given the public a more accurate understanding of his client's defense, which he says the national media distorted and sensationalized. And CBS's Hewitt says he believes strongly that some trials, like the War Crimes Tribunal at the Hague, should definitely be broadcast. ''But a judge should be smart enough to see when a camera's going to turn his courtroom into a circus,'' Hewitt says. At Court TV, Mr. Brill is confident that the more experience the legal system and the public have with cameras in the courts, the more widely they will be accepted. ''I don't think there's any doubt we'll take two steps forward and one back,'' Brill says, noting that Court TV's own survey of judges in trials they have televised found that 98 percent thought the presence of Court TV had not impeded the fairness of the judicial process. ''As it is, I'm 380 for 380 [trials],'' he says. ''That kind of suggests the more we get around, the better off we're going to be.''