Shortly before a judge threw out the $11 million "Born Innocent" damage suit last week, NBC attorney Floyd Abrams assured him that the two-hour television drama did not incite the bizarre child rape that occurred here only four days after the film was shown.

But the jury never got a chance to decide what did, NBC having persuaded the court is dismiss the complaint on First Amendment grounds. The ruling is being appealed by Marvin E. Lewis, counsel for victim Olivia Niemi.

Many Americans may be expected to wonder what could have motivated 15-year old Sharon Smith, aided by two other girls and a boy, ages 10 to 15, to pin down Olivia, 9, on a sand dune and rape her with a beer bottle.

If it wasn't the 2 1/4-minute scene in "Born Innocent" that graphically portrayed a girl, aided by three other girls using the wooden handle of a plumber's plunger to rape the star, Linda Blair, in a reformatory showerroom, what was it?

What else might have been the stimulus to the real-life artificial rape, a crime so rare that Lewis says leading experts in human sexuality had never heard of it?

The question surely will persist, not merely because the press (including NBC) publicized the case, but also because it crystallizes so starkly the public's generally vague unease about the picturing of violence by the unique medium of television.

For NBC, as thee defendant in a lawsuit in which, for the first time, a broadcaster was accused of causing a crime to be committed by viewers, the primary burden was to show that TV drama is constitutionally protected speech. If it isn't NBC warned, freedom of expression throughout the press,, includinng publishing, will be chilled and stifled.

The First Amendment defense prevailed, but Lewis had wanted to try NBC for negligence and recklessness - to make it accountable, with actual and punitive damages, "for the foreseeable results" of a broadcast that, aired in family viewing time, "created an undue risk of harm" to Olivia and possibly others.

NBC praised the film for having exposed "a social problem of tragic proportions - the plight of runaways confined in juveniles institutions and learning from other juveniles convicted of serious crimes." The film is "good and serious and true," Abrams said.

NBC also has said that the rape scene was essential to the film's artistic integrity, although the network sanitized the scene after the furor created by the initial showing.

Notably, however, NBC did not suggest a specific alternative cause for a virtually unheard-of crime. In a phone interview, NBC attorney James J. Brosnahan said that he hypothesized such an alternative in his prepared, but undelivered, opening statement, but that he cannot now disclose it.

Thus Lewis retained virtual carte blanche to publicize his own theory, which is: NBC was accountable for the attack on Olivia "just exactly the same as if they had ordered someone to go out . . and rape her." Here are some of the major points he said he would attempt to make, as summed up in his 3-hour-and-20-minute opening statement to the jury.

Network revenues derive from "modeling" - viewers imitiating persons in commercials by buying the items they promote. In acknowledgement of the networks forbid certain behavior, such as letting a glass of beer touch a person's lips.

For more than a decade, top NBC executives publicly have recognized as valid the warnings by growing numbers of behavioral experts that, in some latently aggressive children and early adolescents, TV violence predictably will stimulate anti-social conduct or even modeling of such conduct.

NBC's own ethics code, which it calls its "conscience," and the industry's volumtary standards forbid gratuious violence - that is, violence presented for its own sake or as an audience stimulant.

NBC board chairman Julian Goodman and fellow executives have assured Congress and fellow executives have assured Congress and investigating bodies that they recognize the potential harm to youth in TV violence and deal with it as "responsible citizens."

In knowing disregard of the experts' warning, of the codes and of the assurances, NBC executives, seeking the highest possible Nielsen ratings and consequent profits, timed the presentation of "Born Innocent" and specifically promoted the rape scene so as to expand the audience with large numbers of children and youngsters.

Lewis told the jury that he would prove this charge partly by showing that NBC had advertised and time-slotted "Born Free," a harmless children's series about lion cubs, to make it appear to be a companion to "Born Innocent." In addition, he said, NBC tried to sign up Walt Disney Productions as a sponsor of the Linda ("The Exorcist") Blair film, which the network picked to launch its 1974 fall drama season.

The rape scene, which "repeated ad nauseam" the thrusting of the handle into Linda, who played a 12-year-old girl, would be described by experts and shown by circumstantial and other evidence as the predictable "proximate cause" of the attack on Olivia. If the film had been shown in a theater, Lewis charged, it would have been "X-rated."

Lewis said a leading behavioral specialist, Dr. R.M. Liebert, would testify that he had warned NBC that a scene such as the "Born Innocent" rape carried a "high risk" of stimulating imitation. Even the author had warned against prolonging the scene, Lewis said.

The film rape scene was particularly apt" to stimulate modeling. Lewis said he would prove, because it was "graphic," "exceptionally long," "instructive" (a how-to-do-it), showed the attackers with a "readily accessible" weapon (anything that "fits into the office of a female"), indicated affinities between the attackers and "millions" of Sharon Smiths, punishment of the attackers, and, finally, was extraneous to the main story line.

In the final minutes of the case, NBC's Abrams said that Judge Robert J. Dossee's dismissal of the suit was "the only thing the First Amendment permitted him to do" and "a marvelous vindication of First Amendment principles." Lewis had a different view: "Our noses are being rubbed in the sewer in the name of the First Amendment."

No matter who was right, it was the First Amendment that enabled the press to carry both views to millions of Americans and, possibly, to stimulate broadcasters to show more restraint.

Even if Lewis wins his appeal, which likely will go to the Supreme Court, years may go by before a new jury would get a chance to decide whether NBC should be financially liable for harm inflicted on a child who was born and was still innocent.