O.n J.ustice

NOT since the Watergate hearings and trial, not since the trial of the Gang of Four in China or the impeachment of Brazil's president has a whole people spent so much time glued to events in a courtroom.

Seldom have so many dinner parties, lunchroom chats, and carpool debates examined in such detail the machinery of justice: police techniques, forensic-lab procedures, legal strategies, and courtroom rules and unruliness. More to the point, seldom have so many Americans examined their own consciences about racism and wife-abuse or woman-abuse (evasively called ''spouse abuse'').

For some in the collective national jury this was Othello reenacted - interracial marital jealousy turned lethal. For others it was a black Dreyfus case - a frame-up by racists in uniform. The actual jury, in contrast to the amateur national jury, was neither split nor much in doubt about ''reasonable doubt'' and police fumbles.

Now that the verdict has been armchaired from every anchor desk and street corner, what can we learn of lasting usefulness?

First, let's puncture two myths:

1. The O.J. Simpson trial was not, despite all the hype, the Trial of the Century. That title more likely belongs to the Nuremberg trials (precedent-setting in determining war guilt by national leaders), the Scopes trial (precedent-setting in vindicating modern science teaching), the Hiss and Rosenberg trials (turning the tide against romantic faith in Stalin's communism), or Brown v. Board of Education (turning the tide against racial segregation).

2. The Simpson trial did not prove that the American justice system is too long-winded, expensive, unbalanced, and prone to showbiz. It simply showed that a few trials err on each of those scores. In most courtrooms, those are not the prime problems. The American justice system has other flaws to fix (read on). But one should not project the extravagances of this one Los Angeles trial onto the thousands of state, municipal, and federal courts in the land. Most are far more efficient, less expensive, les s prone to circus pressures inside and outside the courtroom.

What each society seeks in a justice system is fundamentally what children mean when they say something is fair or not fair. The American criminal-justice system uses a constitutionally mandated trial in front of a jury of one's peers. As most Americans know, the system presumes it is better to risk letting a few guilty parties go because of ''reasonable doubt'' about evidence than to jail or execute one innocent person. Barring an extremely unlikely amendment of the Constitution, that jury system will remain.

So far, so good. But there are problems to be examined and fixed.

The factual (or fact-stretched) drama performed before the jury is carried on in adversarial alternation. The prosecution and defense lawyers are too often determined to win at all costs. One reason the flaws of this adversarial approach have been magnified in recent years is the giant increase in media coverage of pretrial and outside-the-trial publicity by the two sides.

The standard practices of carefully questioning potential jurors or even changing trial venue to make sure jurors do not prejudge a case no longer provide dependable guarantees of unprejudiced minds. Much has been said about the rich unfairly buying a better defense than the average defendant can afford. More attention ought to be paid to the widespread unfair advantage that prosecutors have in this media-drenched age. They often implant unfair influence through sensationalized announcements that stick in the minds of future jurors.

The remedy is not court gag orders on lawyers or media. The cure, imperfect though it may be, lies in continuing tough self-examination by bar associations, law schools, and print and broadcast editors' groups. New norms of self-restraint, attention to fact, fairness to contending sides have to be hammered out and hammered home.

Then there is the matter of jurors' and judges' expertise. In this case, DNA-matching was at issue. In other cases - criminal or civil - highly technical knowledge about chemical pollutants, money-laundering, manipulation of children, or patent law is involved. The same groups mentioned above ought to seek methods of providing more-rigorous screening of so-called ''expert witnesses,'' many of whom are ill-schooled hired guns. Also needed: better pre-schooling of judges and juries on technical matters.

Much has been written about fairness in sentencing. Training of more judges at the National Judiciary College or in bar-sponsored sentencing seminars should help to even out badly varying sentences. Judicial guidelines help. Mandatory sentencing probably does not.

In coming days, we intend to discuss racism and domestic abuse in greater detail. Let us just rest our case here by observing that nothing helps a people be a nation more surely than national discussion of basic issues. Even if it takes a courtroom soap opera to bring that about.

Despite all the hype, this was not the Trial of the Century. That title goes to Nuremberg or 'Brown' desegregation.