A new "right-to-life" battleground has been opened in California through the appeal of a mentally retarded San Jose youngster to the state Supreme Court.

The case, which involves the right of the state to override parental objections and order a probably life-prolonging operation for the child, has the potential of becoming a cause for those who argue that all life is equally sacred, whatever its quality.

A friend-of-the-court brief in behalf of the operation has been filed by the California Pro-Life Council, whose attorney played a key role in originating the case.

Immediately at stake in a legal struggle that attorneys for both sides consider emotional and troubling is whether 12-year-old Phillip Becker should have the open-heart surgery recommended by a heart specialist.

The medical examination of the boy was initiated by a San Jose home for multihandicapped children where Becker lives and where he is considered one of the ablest and most gentle pupils.

Medical testimony at a San Jose legal proceeding last year indicated that the proposed surgery would be likely to prolong Becker's life. Without it, doctors testified, the youth will suffer progressive deterioration from a congenital heart condition that denies him oxygen, and he will have a 50 percent chance of dying by the time he is 30.

The father, Palo Alto patent attorney Warren Becker, testified that he believed his son would be better off dead than alive. The testimony also showed that Becker and his wife, Patricia, after consultation with a doctor and a priest, extensively weighed the options and decided it would be unwise to allow an operation that would prolong Phillip's life in a "warehouse institution" long after his parents, now in their mid-40s, are dead.

Santa Clara County Juvenile Court Judge Eugene M Premo Jr., calling his decision more difficult than a death-penalty case, said the parents had engaged in "very intelligent processes' in reaching their decision. He refused to "second-guess the natural parents," and ruled in their favor.

Subsequently, Premo's decision was affirmed by an appeals court, and the state attorney general, supported by briefs from the pro-life council and the Santa Clara County Bar Association Law Foundation, appealed to the state Supreme Court.

A decision by that court on whether to grant a hearing is expected soon, and lawyers for both sides say the legal battle may be carried from there into the federal courts.

The ultimate decision could have consequences beyond the fate of Phillip Becker, a Down's Syndrome victim. Forty percent of those afflicted with Down's Syndrome, the mental retardation caused by the presence of an extra chromosome at the time of conception, suffer from heart defects.

Additionally, there is widespread concern among those who care for the retarded that the case will become a precedent indirectly establishing that handicapped persons have fewer rights than others.

"I have no doubt that Phillip would have been given the operation if he had been a normal child," said Deputy State Attorney General William Stein, who is presenting the petition for a hearing to the California Supreme Court. "And the Constitution says nothing about mentally retarded persons being denied the equal protection of the law."

The troublesome nature of the case is reflected in references on both sides to euthanasia, or "mercy-killing," decisions.

Stein argued that denying an operation to Phillip Becker is a short step philosophically from refusing operations to those with relatively minor handicaps.

Law Foundation attorney Robert A. Baines, citing a case that found that "a child need not be perfect to have a worthwhile life," referred to Nazi programs of infantcide, which he said also were based on a "quality-of-life" argument.

But in his decision, Premo reflected about what he saw as the dangerous precedent of overriding parental decisions in a case that was not, as he saw it, "a life-and-death situation."

In the absence of any specific neglect, he said, government should respect the wishes of the parents, and he compared the ordering of an operation with a "bureaucratic official deciding that euthanasia is an appropriate thing."

"I'm spooked by the fact that 1984 is coming upon us...when I see this kind of a case coming to court," Premo said.

San Jose attorney Leonard P. Edwards, representing the parents, was careful to avoid a "#quality-of-life" argument when the case was appealed. Instead, he won a unanimous decision in the appellate court by relying on technical points and medical testimony that the mortality rate for Down's Syndrome children in open-heart operations was as high as 10 percent.

The same testimony indicated that there also is a danger to the heart that could require Phillip to wear a pacemaker after the operation.

In fact, physicians, no less than lawyers, are divided about the case. A Palo Alto pediatrician the Beckers consulted supported their decision and contradicted the doctors who favored the operation.

"By his simple and innocent nature, he [Phillip] would be a natural victim to anyone in the community who might take advantage of him by his trust or by taking his money," said Dr. Harry E. Hartzell of the Palo Alto Medical Clinic. "It is difficult for these individuals to fit into modern urban society and, in my experience, they are isolated and rejected."

Hartzell said the decision of the parents was "completely justified," and said it was not worth increasing the expectancy "of a life that I consider devoid of those qualities which give it human dignity."

Such comments are worrisome to some parents of retarded children.

"I am concerned about the future of my Down's Syndrome child," a woman wrote to The San Jose Mercury. "He has all the qualities of human dignity and deserves the right to live."

Phillip Becker has never lived with his parents. According to their testimony, they visit him five or six times a year. According to the testimony of Jeanne Haight, program director of the home where he lives, they visit twice a year.

when the parents declined to approve the operation, Haight consulted with Sal L. Stagnitto, the attorney for the Pro-Life Council. After an investigation, the district attorney of Santa Clara County filed a petition to make Phillip a dependent of the court for the purpose of performing the operation.

Haight described Phillip as a responsible and "very lovable" boy who makes his bed, dresses and feeds himself, helps fold laundry and feed the cat. Dr. Earl Gathman, the pediatrician who recommended the operation, classified Phillip as "one of the brighter Downs - probably falling into 5 to 10 percent of the top of these children in terms of their educational potential."

The parents, who also have two normal boys, impressed the judge who heard their testimony. After an initial negative impression, Premo concluded that the Beckers have demonstrated "intelligence, care, love and a great deal of thought on the subject matter..."

Many of those familiar with the case, whatever their views, have found themselves with contradictory sympathies. As one supporter of the parents puts it:

"This case is too close to the source of our being for anyone to be very facile about it. We're all playing God in this one."