In 1978, following the rape and murder of a Nebraska farm woman by a man out on bail for a previous sexual assault, the voters of that state overwhelmingly approved one of the sternest measures ever enacted by a state to deal with criminal defendants.

It was called the Nebraska "no-bail" rape law: a species of the genus "preventive detention." It is currently under review by the U.S. Supreme Court, which is expected to rule by late spring on what is possibly the most important bail case before the justices in a generation.

In terms no judge could misunderstand, the Nebraska constitutional amendment said there shall be no right to bail for someone charged with forcible rape when the proof is "evident" and the presumption of guilt is "great." A federal appeals court would later call the law an "arbitrary state decree."

The state has no overall statistics on how the law was implemented. There is no doubt, however, that it was: Defendants who otherwise could not have been denied bail were locked up. No one knows how many might have committed crimes had they not been held, but an early survey taken by a public defender demonstrated the risk the state had taken: The first time the law was used, a man was jailed for two months and then found innocent. The second time, a man served 56 days in jail before being found innocent. The third time, a defendant was behind bars 100 days before his trial ended in a hung jury.

The Eighth U.S. Circuit Court of Appeals struck down the law last May as a violation of the constitution's ban on "excessive bail."

The Nebraska law and other pretrial detention proposals under discussion around the country go to the heart of one of the most cherished notions of American justice: that a defendant is innocent until proven guilty in a trial and should not be punished until convicted.

There have always been exceptions. Under the District of Columbia preventive detention law (also up for review at the court), judges following a carefully prescribed procedure may deny bail on grounds that the defendant is dangerous to the community. Judges everywhere may routinely deny bail on grounds that someone is unlikely to show up for trial. Murder suspects, especially those facing the death penalty, are commonly held on the theory that that fate is inherently an incentive to flee. Bail is often effectively denied by setting it so high that a defendant can't possibly meet it.

Nebraskans went much further. The state constitution already made murder and treason nonbailable. (Nobody recalls anyone being charged with treason against the state of Nebraska. Murder has always been treated differently.) The new language added "sexual offenses involving penetration by force or against the will of the victim." They singled out an entire class of defendants in noncapital cases for special treatment without regard to individual circumstances.

For that reason, the appeals court struck it down. "The constitutional protections involved in the grant of pretrial release by bail are too fundamental to foreclose by arbitrary state decree," the court wrote.

The basic question for the Supreme Court is whether there is a "right to bail," and if so, under what circumstances it can be denied. At stake is far more than the Nebraska constitutional amendment. The D.C. preventive detention law might also be affected, along with the Reagan administration's plans for major revisions in federal bail laws. And if Nebraska's law is upheld, other states will undoubtedly follow the lead.

On Sept. 20, 1977, Dennis Sell, 31, a Lexington, Neb., factory worker, appeared before a Dawson County judge and pleaded guilty to sexually assaulting a woman the previous June. The judge ordered a presentence investigation of Sell and then released him on $10,000 bond, requiring an actual cash outlay of only $1,000.

On Sept. 23, Ruth Eby, a county farm wife, was raped and murdered. Her body was discovered in a grove of trees 18 miles west of Lexington. Her husband was in the search party that found her.

On Sept. 28, Sell was charged with the crime, to which he later pleaded guilty. He ultimately also confessed to a second similar murder and was sentenced to life imprisonment.

In the rush of publicity after the murder and arrest, Dawson County Judge Keith Windrum was asked why he had released Sell on bond Sept. 20. First, he said he had been unaware of Sell's previous criminal record at the time. And second, and more importantly, he indicated to reporters that he felt his hands were tied by what was then the law--that bail could be denied only when the suspect might flee.

"I had no reason to think he wasn't going to appear" for sentencing, the judge told the press.

What happened in Dawson County could hardly be considered a rash of crime, and the rest of Nebraska had not experienced anything more than the increase in crime familiar to the rest of the country. Nor did the inspiration for a strong reaction to the murder come from ideologues. It came from people who were scared.

They don't hold big civic meetings or rallies in Nebraska farm country. It isn't their style and they live too far apart. But one by one, the families, friends and neighbors of Ruth Eby communicated their fears to their state senator, Herb Duis.

"They were shocked," said Duis. "They were hurt. They had no realization that someone charged with a crime could be let out like that. They wanted people protected."

Duis, 65, an insurance and real estate broker who had served in Nebraska's unicameral legislature for 14 years, introduced the no-bail bill at the next session. As a proposed constitutional amendment, it required a referendum at the next election. The citizens of Lexington turned out in force for the legislative hearing in January, 1978. Among them was Ellen Eby, the sister-in-law of Sell's victim.

"We want something done," she said. "We have been talking a lot about everyone else's right. Now we have to talk about society's rights."

Considering the bill's implications, there was little public debate and little publicity. The Omaha World-Herald ran a series of articles about the handling of sex-crime defendants and the Sell case. "How Many Sell Cases Does It Take?" the paper editorialized. Civil libertarians opposed the amendment, saying it breached fundamental rights and was a "hysterical" reaction to the crime problem. The Lincoln Journal later joined the opposition. "In our society people are considered innocent until proven guilty," the newspaper said. "Bail is a mechanism to insure that a person will return to court to stand trial: not a mechanism to pass judgment on guilt or innocence." On the first legislative vote, the measure failed. On the second, however, it passed and was signed, without fanfare, by the governor of Nebraska and placed on the ballot.

Some critics of the bill believed that had there been more lawyers in the legislature, conscious of the constitutional considerations, things would have been different. Only four or five lawyers were serving at that time.

Duis says the small proportion of lawyers is, in fact, one of the healthiest facets of the legislature. "Ordinary people should make laws. Lawyers should practice law," he said.

At election time, the "ordinary people" made the law: There were 356,000 voting in favor of Constitutional Amendment No. 6 and 80,000 voting against. Duis says it was the largest margin of victory ever for a substantive proposition.

Ironically, the amendment, as enacted, would have made little or no difference in the Sell case. He had already pleaded guilty and could have been denied bail with ease. And he had pleaded guilty to a reduced second-degree sexual assault charge, not covered by Duis' amendment.

One man has largely carried out the challenge to the law. Bennett G. Hornstein, a public defender in Omaha, fought it at election time, appealed it unsuccessfully to the Nebraska Supreme Court and then took it to the federal courts. On the other side, assistant Nebraska attorney general Terry R. Schaaf, has defended each attack.

The Nebraska law, says Schaaf, "was a reaction to a particular problem. They the people feared rapists. They've done something that makes them fear them less. Scholars, journalists and lawyers can debate the constitutionality. But the average citizen is convinced to a moral certainty that they've done the right thing."

Hornstein responds: "It may have been a kind of cathartic exercise, but that doesn't justify it. . . . If it is upheld, the floodgates will open. Every state in the country will do it. It's like voting for motherhood and apple pie. People don't visualize themselves as defendants."

The legal debate is more complicated. The Eighth Amendment to the Constitution says: "Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments be inflicted."

The Supreme Court has never ruled explicitly, however, that the excessive bail provision must be obeyed by the states. More importantly, the court has never precisely defined it.

Nebraska argues, first, that the law does not prohibit bail for anyone. It simply removes a defendant's right to demand it. A judge may still allow release.

Secondly, Schaaf contends that the Eighth Amendment "does not create a fundamental right to bail. . . . Rather, it only provides that bail shall not be excessive in those cases where it is otherwise proper to grant bail."

Finally, in an argument of increasing attractiveness to the Burger court, Nebraska says the federal courts should be exceptionally wary of striking down the expressed political will of the people. The law was a "reasonable" means to achieve a reasonable end, the state says, and the amendment represented "the fundamental and organic law of the state" which requires federal intervention only when the U.S. Constitution has been clearly breached.

Hornstein is representing Eugene L. Hunt, a convicted rapist who was denied bail before his trial.

While Supreme Court precedent may not explicitly create a "right to bail, the practice in this country over the past 200 years has created the right. It is by no means an "absolute" right, he says. But its denial "requires a consideration of the totality of the circumstances" of a defendant. Nebraska does not allow consideration of these other factors."

Even if the Eighth Amendment creates no right to bail, Hornstein says, a defendant has a general right to liberty protected by other parts of the Constitution, such as the Fourteenth Amendment. The Nebraska law, in its sweep, he says, was an act of overkill that restricts that liberty without attacking the problem it set out to solve.