THOUGH the O.J. Simpson case is over, the United States justice system is just beginning to go on trial.
Two days after the acquittal of Mr. Simpson cast a panorama of stunned white faces and jubilant black faces in America's living rooms, talk has not subsided about the kind of justice served by the verdict and the lessons to draw from it.
Few Americans believe anything about this trial was normal. Still, aberration or not, the Simpson case could have a lasting effect on US law enforcement and society at large. Experts say perceptions about the verdict could produce a kind of slippery slope of distrust - in the area of race relations, trust in police work, gender relations, and the American legal system.
Along with race, three major issues stand out in the aftermath of what has been called the trial of the century:
* ''Jury nullification,'' or a jury's response to emotions rather than evidence.
* The need to reform law enforcement, in the wake of a prosecution team that had as its star witness a detective exposed as a racist.
* Domestic violence, following a case that took on racial overtones, rather than the message about violence against women many feminist groups had hoped for.
''Jury nullification'' is the legal buzzword of the hour. It describes what happens when issues or passions outside a courtroom play so strongly on a jury that they ignore what the law says about deciding a case. Nullification usually arises in hot political or civil rights cases. But according to Robert Pugsley of the Southwestern School of Law in Los Angeles, it is increasing seen in racially charged cases like the Reginald Denny and Rodney King trials in Los Angeles.
''We are likely to see more [nullification] as distrust of government grows,'' Dr. Pugsley says.
The trend worries legal scholars since it is a practice that is easy to abuse; judges typically outlaw arguments that nullify.
Yet in The People v. Simpson, scholars disagree whether Johnnie Cochran's final arguments asking the jury to ''send a message'' to the Los Angeles Police Department was nullification.
Abbe Smith, deputy director of the Criminal Justice Institute at Harvard University, says it probably was. ''The Simpson decision comports with popular wisdom about what minority juries do in cases raised to this level,'' she says.
Yet for Ira Mickenberg, director of training for the Wisconsin State Public Defenders, the verdict meant that members of the Simpson jury merely had ''reasonable doubt'' about convicting Simpson.
''A good lawyer puts the jury in a mood to be receptive; I think having no weapon, no eyewitness, and a police officer who lied was what clinched it,'' he says.
Dr. Mickenburg compares the case to the ''Panther 21'' trial in New York in the early 1970s where, in the longest and most expensive trial in New York history, a jury took only one hour to acquit 21 Black Panthers of sedition. In a book titled ''Juror Number Four,'' juror Edward Kennebeck said that after months of mountainous detail, the jury foreman simply asked if any other jurors had doubts - and half said yes. The men were acquitted.
So far, the Simpson jury has been mostly sphinx-like in its refusal to discuss the case with lawyers or the press. One juror, Lionel Cryer, told the Los Angeles Times on Tuesday that it was potential evidence tampering, not race, that guided the jury's decision.
The main legacy of Simpson may be an effort to weed out good cops from bad, say a variety of criminal justice experts - given that the prosecution may have lost the case on former detective Mark Fuhrman's questionable testimony.
But the needed reform will come only if prosecutors hold the police accountable, and they themselves police their ranks.
''There are people like Fuhrman on police departments across the country,'' says Mary Powers of the National Coalition for Police Accountability in Chicago. ''I hope this will do something to break the code of silence'' among fellow officers.
Prosecutors know who the police officers are who make bad convictions and lie on the stand, says Joseph Nursey, a lawyer in Atlanta.
''But it will take a fundamental change in the way prosecutors blink at law-enforcement misconduct,'' says Mr. Nursey, ''since prosecutors rely on these cops to get what they most want: convictions.''
Had Simpson been found guilty, according to Nancy Rhodes, editor of a police newsletter in Syracuse, N.Y., ''I think it would have retarded the burgeoning reform movement.''
FOR many women in and out of criminal justice, the O.J. verdict sends a chilling message in a country where some 1,500 women were murdered by their husbands or boyfriends last year.
It will ''definitely affect'' the willingness of women that are being abused to come forward, says Leslye Orloff, founder of a legal coalition to protect battered immigrant women in Washington, D.C.
Dr. Smith of Harvard says her main concern is that ''the defense turned this into a race case, when it was a sexual violence and domestic violence case.''
Still, the O.J. case has shown an important ''spotlight'' on the problem of domestic violence, says Kathryn Rodgers, executive director of the NOW Legal Defense and Education Fund.
''The media can't just walk away from this issue,'' she says.