Same-sex couples who raise children are lawful parents and must provide for them if they break up, the California Supreme Court ruled Monday.

The precedent-setting decision puts former gay and lesbian couples on equal ground with unmarried heterosexual couples who break up and marks the latest decision by the court recognizing rights of same-sex couples (search).

The justices, ruling in three cases, announced for the first time that custody and child support laws that hold absent fathers accountable and protect children from the stigma of illegitimacy also apply to estranged gay and lesbian couples who used reproductive science to conceive.

In doing so, a Marin County woman was granted the right to be the second mother of twins after the birth mother moved out of state. The court also ruled that a lesbian woman cannot avoid paying child support for her former partner's biological children, and that another woman could not go to court to terminate the parental rights of her former lover, years after obtaining a court order stipulating they were both parents.

"The court is now protecting the children of same sex parents in gay families in the same way children are protected with heterosexual couples in heterosexual families," said Jill Hersh, who argued the unnamed Marin County woman's case before the justices.

Courtney Joslin, an attorney with the National Center For Lesbian Rights (search), said "This is the first time any state supreme court in the country has made this ruling."

The court followed its 2002 decision in which it said men who establish themselves as parental figures may become legal fathers even if they did not help conceive the child.

"These legal principles apply with equal force in this case," Justice Joyce Kennard wrote in a concurring opinion in a case ordering a lesbian woman to support her former lover's twins. Being a legal parent, Kennard added, "brings with it the benefits as well as the responsibilities."

Emily B., the El Dorado County woman whose former lover, Elisa B., must now pay to support the children, said she might be able to get off of welfare now.

"I'm absolutely overjoyed today," she said.

The cases are Elisa B. v. Superior Court, S125912; K.M. v. E.G., S124643 (search); Kristine H. v. Lisa R., S126945.