The California Supreme Court ruled yesterday that a wife who supports her husband through professional school may be entitled to recover those costs plus interest if the marriage breaks up.

In a 5-to-1 decision, the court seemed to defer to the California Legislature, which last August passed a law providing for the reimbursement of education costs in addition to alimony payments. Earlier law had no such provision. The new ruling went into effect at midnight.

Both the decision and the new legislation, part of the evolution of divorce law nationwide, arose from Sullivan v. Sullivan, a celebrated case in which a southern California woman claimed her husband's medical degree -- and thus his future earnings -- was community property in their divorce settlement.

Janet Sullivan worked for 10 years to support her husband, Mark, while he studied to become a urologist. They were divorced in 1978, before his practice began to thrive. Representatives of women's groups and the medical establishment filed opposing "friend of the court" briefs in the case.

In yesterday's ruling -- which came down nearly two years after the oral arguments -- Chief Justice Rose Bird, writing for the majority, gave a green light for Janet Sullivan to pursue a monetary award, but appeared to leave open the question of whether she might also be entitled to her ex-husband's future earnings or any part of the value of his medical degree.

California assembly member Alister McAlister, who was closely involved in the development of the legislation, said it "does not provide any right to future earnings. It doesn't say that a medical degree is community property and it doesn't say that it's not."

Sacramento lawyer Fred Hiestad, who filed an amicus brief for Mark Sullivan on behalf of the California Medical Association, said he was satisfied with the court's ruling, and said the new state law is "fair."

"Our main concern was, are you going to make medical degrees the property of someone else, and how do you put a value on that degree?" he said. "It would lead to all kinds of litigation."

There may be more litigation anyway. Morris Sorenson, Mark Sullivan's lawyer, said, "The court said the case should go back to trial court for further proceedings under the new legislation.

"The legislation says that in addition to awarding alimony, the trial judge must consider the enhanced earning power of a spouse who acquires an education during the term of the marriage, and also must consider the spouse's contribution." Sorenson added, however, that consideration of these factors in a divorce settlement does not guarantee a monetary award.

Sorenson said his client, who was unavailable for comment, "was not grossly surprised by the ruling." He said Mark Sullivan could take the case back to the trial court or settle it out of court, but that he had made no decision.