WASHINGTON AND LOS ANGELES — EVER since it began more than 12 months ago the trial of O.J. Simpson has gripped America as few other criminal cases this century have. Its characters - the jealous husband, the battered wife, the clueless houseguest - were transformed into actors in a morality play. Attorneys wove its evidence into stories as fascinating as any thriller plot.
But now the sensational story-telling has ended. Today the judgment begins, as the trial's 12 jurors start their first day of deliberations on Simpson's fate. Will they see the case as the prosecution has framed it, as an explosion of domestic violence? Or will they view the celebrity defendant as his attorneys portray him, the victim of bigoted police-force collusion?
It's a stark choice - and one that has deeply split the American public along racial lines. The start of the trial's decisive phase came as crowds gathered outside the courthouse and Los Angeles police went on alert in preparation for civil unrest after the verdict.
Whatever its merits as justice, the Simpson trial has revealed an astonishing gap in the way blacks and whites view the workings of the country's law-enforcement system. The disparity is so great that even President Clinton has been moved to say that the case should be seen as a verdict on an individual, not US society as a whole.
''I'm concerned about it,'' said Clinton on Friday. ''I hope the American people will not let this become some symbol of the larger racial issue in our country.''
The success of the Simpson defense team in presenting the case in racial terms - and particularly their exposure of prosecution witness former detective Mark Furhman as a lying racist - has led some legal experts to predict a hung jury or acquittal. But many admit that armchair cross-examination is easy. No one really knows what will happen in the jury room.
''So much is dependent on the dynamics of the jury room,'' says Myrna Raeder, an American Bar Association criminal justice expert. ''This may turn on who the foreperson is and how they control the process of deliberation and compromise.''
If nothing else, the end of testimony in the Simpson trial may mark the end of television's first live-broadcast miniseries. The lurid case proved irresistible to viewers: CNN viewership went up 500 percent after it began broadcasting proceedings live. Since mid-1994, ABC's Nightline has devoted some 15 percent of its air time to discussion of O.J.
A byproduct of this popularity may have been a mass audience education in the faults and virtues of the American legal system. A public used to unrealistic Perry Mason-like portrayals of court proceedings saw the real thing, from ''sidebar'' discussions held out of the jury's hearing, to the limits of rules of evidence and the implication of Fifth Amendment protection against self-incrimination.
It's important to remember, however, that in some ways the Simpson trial is no more reflective of day-to-day American justice than is ''Murder, She Wrote.'' Few murder defendants have the money to hire a team of expensive lawyers. Few cases are so notorious that the state throws as much effort into prosecution as it can muster.
''Most criminal cases look nothing like the O.J. trial,'' and in that sense it gives a false impression, notes Abbe Smith, deputy director of the Criminal Justice Institute at Harvard Law School in Cambridge, Mass.
The starts and stops and endless wrangling over details that characterized the Simpson case were unusual. But ''if it were your future on the line, you would want the criminal-justice system working on your behalf as it has for O.J., with every bit of evidence presented up and down, and left and right,'' says American University professor Richard Stack, the author of a book on public relations in criminal cases.
The Simpson defense team, notes Mr. Stack, crafted several tiers of messages for the jury. The first showed Simpson as an aggrieved family man who missed his kids. The second depicted him as an African-American at the mercy of a hostile white justice system. A third portrays him as the victim of police who bungled their investigation, whether through racial animosity or incompetence.
The prosecution, by contrast, focused less on crafting messages than on the mountain of circumstantial physical evidence that links Simpson to the crime. They tried to make the jury believe that defense efforts to bring the issue of race into the case were nothing but a smoke screen.
''In his closing arguments, [defense attorney] Mr. Cochran appealed strongly to the jury's emotions,'' says Robert Pugsley, a professor at Southwestern University School of Law in Los Angeles. ''The prosecution, by contrast, is imploring the jury to look dispassionately at all the evidence.''
Since the trial began, Americans have judged these efforts differently, depending on the prism of racial experience they see them through. Polls have consistently shown blacks are much more likely than whites to believe Simpson is innocent. A ''Dateline NBC'' survey released last week found that only 2 percent of black respondents believed Simpson guilty of first-degree murder. Forty percent of whites thought he was guilty.
The question thus becomes whether the defense has planted enough doubt about the case's physical evidence to make its attacks on the police ring true with jurors.
''I can personally justify a verdict in either direction without descending into the racism question - i.e., on the basis of differing interpretations of the evidence,'' concludes Ms. Raeder of the ABA.