SAN FRANCISCO (AP) – The California Supreme Court heard arguments on whether private country clubs can refuse spousal discounts to lesbians who by law cannot marry.

During an hour of arguments on May 26, the seven justices did not show their hands on how they might rule in a case that is expected to factor into the state’s ongoing courtroom battle for same-sex marriage.

“It’s a difficult case,” Justice Joyce Kennard said of the suit brought by a San Diego lesbian couple.

The dispute centers on Birgit Koebke, 48, who pays the Bernardo Heights Country Club in San Diego about $500 a month in membership fees. Married members can have their children, grandchildren and spouses play golf for free.

Under club rules, Koebke must pay as much as $70 for her partner, Kendall French, 43, to play a round of golf, and French can only be Koebke’s “guest” six times a year.

“Why should a business be able to treat these people differently?” the couple’s attorney, Jon Davidson, asked the court.

Club attorney Jeremy Rosen told the justices that, despite California’s 2005 domestic partner law nearly guaranteeing same-sex couples the same legal footing as married couples, the country club is not unlawfully discriminating against the pair.

The law allows for businesses to distinguish between the married and unmarried in certain circumstances, Rosen said, adding that the club is making the distinction to limit how many people will use its “scarce resources.”

If the high court agrees with the couple, Rosen said, “no business could make any distinction between any married person and any unmarried person.”

Even the state’s domestic partner law allows marriage discrimination because it precludes gays and lesbians from filing state income taxes as married couples, Rosen noted.

“The state tax code intentionally discriminates,” he said.

Marital discrimination, he said, is when a landlord refuses to rent to an unmarried couple, or an employer refuses to hire a single mother.

The justices’ decision, expected in 90 days, will become lodged in the ongoing legal battle for same-sex marriage in California. That dispute is headed to the appellate courts, and concerns a trial judge’s decision declaring unconstitutional California’s ban same-sex marriage.

In that case, Attorney General Bill Lockyer argues that the 2005 domestic partner law provides so many martial benefits to same-sex couples that banning same-sex marriage does not discriminate against gays and lesbians.

If the Supreme Court sides against Koebke and French, proponents of same-sex marriage will invoke the decision as another reason why same-sex marriage should be legal, Davidson said.

Outside court, French lashed out at the club, claiming the managers simply want to keep out gays and lesbians.

“We’re not trying to be troublemakers,” Koebke added.

Justice Janice Rogers Brown, whose nomination to a federal appeals court is expected to be heard in the U.S. Senate this week, was the only justice to remain silent during the hearing.

The case is Koebke v. Bernardo Heights Country Club, S124179.