MIGHT PEOPLE in the District of Columbia wanted to have seen the trial of Mayor Barry on television or at least taped excerpts of the testimony on the evening news? In 45 states, the trial of a government leader on criminal charges would have been covered by cameras, but not in Indiana, Mississippi, Missouri, South Carolina, South Dakota or here. Cameras are banned from these courtrooms as they are, with one exception, from all federal trial and appellate courts. Only the U.S. Court of Military Appeals has taken the plunge. It has allowed video coverage in three cases during the past 18 months.

In the recent past, federal judges -- and perhaps local judges here -- have taken their cue on this issue from the top. Former chief justice Warren Burger opposed any change in the rule barring cameras from the courtroom, and a committee he appointed to review the matter in 1983 turned down a reform proposed by a media group that included The Washington Post Co. Chief Justice Rehnquist, however, was more receptive to the idea of change, and now after a second study, it is about to happen. A special committee of the Judicial Conference headed by Judge Robert Peckham of the Northern District of California has recommended a pilot program for the federal courts. If the conference, which is expected to vote on the recommendation today, agrees, cameras will be allowed in two appellate and six trial courts on an experimental basis. Only those courts that volunteer to participate will be chosen for the three-year project and for now at least, only civil cases will be covered. In spite of these limitations, the barrier in the federal courts will be broken and expanded coverage can be expected.

Ten years ago, the idea of television cameras in the courtroom -- or in Congress -- was not even considered realistic. Bulky equipment, bright lights, intrusive microphones and the possibility of posturing judges and attorneys were all factors that weighed against change. But technological improvements that eliminated the first three and experience in the states demonstrating that bench and bar behaved reasonably on camera led to widespread change. There is even some testimony from the states that the presence of a camera encourages better preparation, more decorum and an improved adherence to schedule.

These are welcome side effects, but the main argument for cameras in the courts is the public's access to an important government forum. Now that the federal courts are about to enter the video age, perhaps the five reluctant states and the District of Columbia will follow. Holdouts are shortchanging their citizens and missing a great opportunity to improve public understanding of the judicial system.