Less than two weeks after legalizing same-sex marriages in California, the state Supreme Court had some tough questions Wednesday for a lawyer defending doctors who refused on religious grounds to provide artificial insemination for a lesbian.

The case of Guadalupe Benitez presents the justices with issues of civil rights and discrimination from a different perspective than the one they addressed May 15, when they overturned the state's opposite-sex-only marriage law.

Benitez sued North Coast Women's Care, a fertility clinic in Vista (San Diego County), and two of its doctors who refused in 2000 to provide intrauterine insemination. She said Christine Brody, her treating physician, and Douglas Fenton, the clinic's medical director, told her their Christian beliefs prohibited them from furnishing the infertility treatment for a lesbian couple.

Benitez's lawyers said the doctors gave the same explanation in sworn declarations but asserted in later depositions that they would refuse the treatment to any unmarried couple. The distinction is potentially important if the case goes to trial because, at the time, California courts had ruled that state law barred businesses from denying service to gays and lesbians but had not yet decided whether the law also prohibited discrimination based on marital status.

The state Supreme Court outlawed such discrimination in 2005. It has not said, however, whether it was illegal before then.

The issue at Wednesday's hearing in San Francisco was whether the doctors, or any business owners or employees, can invoke their religious beliefs to justify refusing to provide service to a particular person or group. The doctors in Benitez's case are asking the court to let them rely on their religion as a defense in her pending damage suit.

"The law should not allow one side to trump another side's rights," said Kenneth Pedroza, lawyer for the doctors and the clinic.

Arguing that California's Constitution contains an ironclad guarantee of religious freedom, Pedroza said the rights of doctors and patients can both be served as they were in this case, when his clients referred Benitez to a physician elsewhere who was willing to provide artificial insemination. The treatment did not succeed in impregnating her, but she later became pregnant through other means and is raising three children with her partner.

Pedroza was questioned skeptically by Justice Carol Corrigan, who dissented from the court's 4-3 marriage ruling and argued that the rights of gays and lesbians to wed should be conferred by the people and not the courts.

On Wednesday, Corrigan suggested there are only two legal options for doctors with strong religious beliefs: Choose a field of practice that doesn't conflict with those beliefs or provide their services to anyone who needs them.

Corrigan said Pedroza's clients had told Benitez, in effect, "I am not going to do it for you because of who you are."

No, Pedroza replied, each doctor had simply let Benitez know that "I am not going to compromise my sincerely held religious belief."

Chief Justice Ronald George, author of the majority opinion on same-sex marriage, also challenged Pedroza, asking whether he would claim a right for doctors to deny service to ethnic minorities on religious grounds.

Pedroza said he that knows of no religious doctrine that forbids any type of medical treatment for minorities but that the law must accommodate any doctor who sincerely holds such a belief.

A ruling is due in 90 days. After the hearing, Benitez, 36, said she wasn't trying to interfere with the doctors' religious beliefs. But she said they needed to be reminded that they are in the business of practicing medicine, "not abandoning the patient."

It hurts "to be told you're not worthy of being a mother or having a child," said Benitez, standing alongside Joanne Clark, her partner of 18 years.

The court has rejected others' claims that they are exempt from civil rights laws because of their religious beliefs. In 1996, the justices required a landlady to rent to an unmarried couple despite her religious objections, saying she must follow the law or find another vocation.

A 2004 ruling required Catholic Charities to abide by a state law that required company-sponsored health plans to offer contraception for women. The court said Catholic Charities, which serves and employs many non-Catholics, did not qualify for the exemption the law provides to religious employers.

Benitez's lawyer, Jennifer Pizer of the Lambda Legal Defense and Education Fund, said Wednesday that those rulings provide ample authority for the court to require all doctors to abide by the state's Unruh Act, which protects business customers against discrimination. She said doctors who have religious or moral objections to a certain procedure or treatment - abortion, for example - can refuse to provide it to anyone but cannot be selective.

"Doctors can choose their procedures," Pizer told the court, "but they can't pick and choose among their patients."

The case is North Coast Women's Care Medical Group vs. Superior Court (Benitez), S142892.