San Francisco ? The California Supreme Court could decide that there are two kinds of same-sex couples: those who can’t get married, and those who already did.

A ruling that upholds both voters’ November decision to ban gay marriage and the 18,000 same-sex marriages conducted earlier in California could come off as a safe compromise. But it also promises to keep alive an issue that has split the state as few others have.

Such a decision would give same-sex marriage advocates an avenue to pursue a federal appeal, and an argument for compelling the state to, as Associate Justice Ming Chin put it, “get out of the marriage business.”

Justices on the high court appear hesitant to overturn Proposition 8, while also reluctant to invalidate same-sex marriages performed before it passed, legal observers agreed Friday.

During Thursday’s oral arguments on a trio of lawsuits seeking to overturn the ban, Chin and Chief Justice Ronald George seemed to anticipate the difficulty in reconciling the state constitution’s promise of equality with its commitment to giving voters wide discretion to pass laws.

Chin, who was not part of the court majority that ruled last year to legalize same-sex marriage, twice asked whether the court should direct the state “to employ non-marriage terminology” and instead make only civil unions or domestic partnerships available to all.

Gay-rights lawyers and Pepperdine University law school dean Kenneth Starr, who was representing Proposition 8’s sponsors, agreed that making marriage the province of religious institutions was one way, however unanticipated, around the problem.

“There is a long tradition of requiring different parts of the California Constitution to be harmonized,” said David Cruz, a constitutional law professor at the University of Southern California who is not involved in the case. “It’s not necessarily what the voters intended — their only clear intent was to stop gay people from getting married.”

Although the 14-word measure holds that “Only marriage between a man and a woman is valid or recognized in California,” the justices indicated their discomfort with dissolving the unions of gay and lesbian couples who married before the election.

Having some gay couples allowed to stay married while others are prohibited from saying “I do” would provide legally plausible, if politically debatable, grounds for an appeal under the equal protection clause of the U.S. Constitution, according to Cruz.