SAN FRANCISCO -- A federal appeals court Tuesday rejected the last remaining appeal argument challenging San Francisco's pioneering domestic partners law.

The 9th U.S. Circuit Court of Appeals, in a ruling issued in San Francisco, said the city law does not conflict with a state law that allows for registration of domestic partners.

The argument was the only unresolved issue in a lawsuit filed by S.D. Myers Inc., an Ohio electrical company that said the law was contrary to its religious and moral principles.

The Equal Benefits Ordinance requires contractors doing business with the city to give unmarried employees and their partners the same benefits as married couples.

The measure was the first of its kind in the nation when it went into effect in 1997.

A three-judge panel of the appeals court said the city and state laws cover different subjects because the state law is concerned only with registration procedures and does not address discrimination or employee benefits.

Circuit Judge Alfred Goodwin wrote, "The measures regulate wholly distinct subject matters and do not contradict each other."

Other aspects of the city law were previously upheld by the appeals court in earlier rulings.

Chief Deputy City Attorney Therese Stewart said, "This is the last nail in the coffin of the religious right's challenge to San Francisco's ground-breaking Equal Benefits Ordinance."

Stewart said the San Francisco measure has had a "huge ripple effect" nationally by causing large corporations and health insurance companies to provide benefits for domestic partners. The law applies to thousands of companies doing business with the city.

Gene Kapp, a spokesman for the Virginia-based American Center for Law and Justice, which represented S.D. Myers, said the group had no immediate comment on the ruling or on whether the company will appeal further.

Benefits covered by the ordinance can include bereavement leave, family medical leave and health and pension programs.

S.D. Myers said when it filed its lawsuit in 1997 that giving health insurance to unmarried partners would be approving a lifestyle contrary to its Christian principles.