BENNINGTON, VT. -- Just before the morning break one summer day in 1982, Virginia Green was summoned to the personnel office at the Johnson Controls plant here and told she no longer had her job stacking automobile battery plates.

Because the position exposed her to high levels of lead, and because Green -- then 50 -- was still capable of bearing children, she was given a new job: washing the respirators of men she had worked beside since the company first hired women a decade earlier.

Eight years later, Green still flushes with anger when she talks about Johnson Control's "fetal protection" policy. "I'll be bitter to the day I die," Green said of the edict, which forced her off a job she wanted to keep so badly she considered sterilization until her doctor advised against it.

Green, and other female workers at Johnson Controls' 13 battery manufacturing plants nationwide, believe keeping fertile women out of the well-paying factory jobs that entail lead exposure is illegal sex discrimination, a throwback to when women were treated as childbearing vessels in need of protection through devices such as maximum hours laws.

"What is really at stake in this case," in which the Supreme Court will hear oral arguments Wednesday, "is the future employment of women, particularly in less traditionally female jobs," said the women's lawyer, Marsha Berzon. "If the company wins here, job segregation will vastly increase."

Milwaukee-based Johnson Controls views its policy as both legally sound and morally mandated, a laudable corporate response to two hard facts: The company needs to use lead in its batteries, and high lead levels pose potentially severe hazards to a developing fetus.

"We put in the policy because we believed it would be wrong to knowingly expose unborn children to serious physical harm," said company spokeswoman Denise Zutz. "We believe we've got a responsibility not only for the health and safety of our employees but also of their children."

Auto Workers v. Johnson Controls will be the high court's first examination of the ethical, medical and legal conundrum presented by fetal protection policies.

The argument comes at a time when women are becoming more integrated into previously all-male workplaces even as evidence is mounting of a minefield of potential reproductive hazards.

The case calls on the court to instruct employers on how they will be allowed to balance their legal obligation not to discriminate on the basis of sex with their desire to protect workers' offspring from harm -- and shield themselves from the risk of liability suits.

It may appear the parties have their positions backwards: a company asserting a need to maintain workplace safety and a union fighting safety restrictions. But those opposed to the policy, including environmental as well as women's rights groups, are adamant that such an interpretation sets up a false conflict between women and fetuses. Emphasizing evidence that there is a risk to the offspring of male workers as well, they say the focus should be on the need to keep workplaces safe for all employees and on the problems for women and their families if they are shut out of such jobs.

"I have never advocated the right to a dirty workplace," said Joan E. Bertin of the American Civil Liberties Union Women's Rights Project. "I am advocating that employers be held to their obligation to maintain a clean workplace for workers of both sexes."

Bertin and others opposed to fetal protection policies argue that the instinct of companies to solve a potential problem by banning women reflects a reluctance to have women in such jobs in the first place -- and the plentiful supply of men to replace them.

"The willingness to exclude women . . . is really a declaration that we can get along without the women," said Berzon, who says the decision should be up to women.

They also question the sincerity of corporate concern for fetal health since the economic impact of the policy -- keeping women out of better-paying jobs -- may be to cause even greater harm through malnutrition or poor prenatal care.

Johnson Controls and business groups supporting the company say its policy is simply "good corporate citizenship," as the U.S. Chamber of Commerce describes it.

"Businesses are often criticized for not taking responsiblity," Zutz said. "We can't be responsible if the child gets hit by a car in front of their house, but we feel obligated to take the responsibility for what occurs in our plants."

The prevalence of fetal protection policies is unclear, at least in part because companies do not trumpet the restrictions. Among the companies that have used them are American Cyanamid Co., Olin Corp., General Motors, Gulf Oil, B.F. Goodrich, Dow Chemical, Du Pont, Union Carbide and Monsanto, according to the ACLU.

Whatever the court does in the Johnson Controls case is likely to determine the future of such restrictions. Dissenting from the federal appeals court ruling upholding the policy, Judge Frank H. Easterbrook described the dispute as "likely the most important sex-discrimination case" since the adoption of the federal job discrimination law in 1964, and warned that it could close as many as 20 million jobs to women.

In a case where the parties agree on very little else, no one doubts that lead exposure presents the risk of harm to workers and their offspring. Children exposed to high levels of lead in the uterus may develop severe learning disabilities. In 1977, Johnson Controls warned female workers of the potential for harm, and recommended that they not take jobs in high-lead areas if they were considering having families.

Five years later, after eight of about 275 women had become pregnant -- and one child, the company said, had elevated lead levels -- the company adopted the policy at issue before the court. Fertile women already in jobs with lead exposure could only remain in those positions if they were able to keep their lead exposure below a certain level; otherwise they would be transferred to new positions, at the same pay.

Other fertile women (those under 70, unless they supplied medical proof to the contrary), need not apply, the company said: the risk of unplanned pregnancies and the body's ability to store lead for months after exposure, meant it could not simply wait until women became pregnant to move them out of jobs involving lead exposure.

The United Automobile Workers challenged the policy on behalf of Green and other women, as well as a male worker denied a transfer out of a job involving lead exposure when he was considering having children. The union argued, among other things, that there was evidence of harm to offspring of male workers also.

A U.S. district court, and then the appeals court, threw out the suit. The appeals court, dividing 7 to 4, treated the policy not as one involving intentional bias against women but as a "neutral" rule that merely had a "disparate impact" on women, and could therefore be justified simply by the company showing it was a "business necessity."

The appeals court, which dismissed as "speculative" evidence of male reproductive harm, also said the company could meet the higher test of proving that infertility was a "bona fide occupational qualification," the tougher justification required in cases of outright discrimination.

Richard Posner, one of the leading conservatives on the court, dissented, saying the case should be sent back for a full-scale trial under the tougher standard.

The other conservative, Easterbrook, warned that the majority's position "would allow employers to consign more women to 'women's work' while reserving better-paying but more hazardous jobs for men."

In this town of 10,000, where Johnson Controls is the largest employer, there are just 12 women among 280 factory workers. Of the women hired since the policy went into effect, even for jobs that do not require lead exposure, none are "fertile females," as they are known among workers.

Joanne Leard, the union's health and safety monitor, said that when the policy was adopted, "It was like we were wearing a sign. Everyone knew who was fertile and who wasn't. They guys had a ball with it . . . . They'd come on to you, naturally, if they figured they could have some safe sex."

Leard -- whose husband, son and son-in-law work at the plant -- believes lead is a reproductive hazard for both sexes, and that workers of either sex should be allowed to move off the jobs if they are planning families.

Green, who went from $2 an hour at a furniture factory to $10 an hour at Johnson Controls, said that as the court weighs her lawsuit, she thinks about the future of her daughter, Kelly, a high school senior.

"I would like her to {work at the plant} but they won't take her," Green said. "If nothing else is ever done about it, I would like to see that she could get a job at a good-paying place rather than working at McDonald's."