Gay and lesbian couples in California have a constitutional right to marry, a San Francisco Superior Court judge ruled Monday.
The ruling by Judge Richard Kramer is just the first step in a case that is headed for the state Supreme Court, probably sometime next year. But it marks the first time that a California judge has declared unconstitutional the state law that defines marriage as a union between a man and a woman.
"I never thought I would see it in my lifetime," a jubilant Kate Kendell, executive director of the National Center for Lesbian Rights, said outside the courthouse. "It's an amazing day for justice, an amazing day for lesbian and gay families."
The ruling comes more than a year after about 4,000 same-sex couples exchanged marriage vows at San Francisco City Hall after Mayor Gavin Newsom ordered that the city clerk issue them marriage licenses. The state Supreme Court declared the marriages invalid last August and ruled that Newsom had exceeded his authority in giving the marriages the go-ahead.
Monday's ruling did not revive those marriages but - if it stands - will allow same-sex couples to marry in the future. Currently, only Massachusetts allows same-sex couples to wed. A trial judge in New York has ruled that state's same-sex marriage ban unconstitutional. That decision is on appeal, and a decision on same-sex marriage is pending in Washington state.
In his 27-page decision, Kramer - an appointee of former Gov. Pete Wilson, a Republican - said the state's ban on same-sex marriage violates "the basic human right to marry the person of one's choice," and has no rational justification.
Rejecting California Attorney General Bill Lockyer's argument that California is entitled to maintain the traditional definition of marriage, Kramer said the same explanation was offered for the state's ban on interracial marriage, which was struck down by the state Supreme Court in 1948.
The judge also rejected arguments by opponents of same-sex marriage that the current law promotes procreation and child-rearing by a husband and wife. "One does not have to be married in order to procreate, nor does one have to procreate in order to marry," Kramer said.
E-mail Bob Egelko at begelko@sfchronicle.com
Superior Court Judge Richard A. Kramer struck down two California laws that limited marriage in the state to a union of opposite-sex couples. The ruling came one year after San Francisco made worldwide headlines when it opened its city hall to same-sex weddings over Valentine's Day weekend through March 11 2004.

Kramer said the two California laws violated the state's constitutional guarantees of privacy and a legal concept called due process - which tries to ensure each person is treated equally by the law. "The denial of marriage to same-sex couples appears impermissibly arbitrary," Kramer wrote in the opinion released Monday.

In his decision, Kramer cited United States Supreme Court case law ranging from ''Brown v. Board of Education'' to ''Lawrence v. Texas'' in a step-by-step dismantling of legal arguments against same-sex marriage. Including the following excerpts:
*'''Traditional definition of marriage:''' "Same-sex marriage cannot be prohibited solely because California has always done so before."
*'''With California's domestic partner laws, gays don't need marriage:''' "That California has granted marriage-like rights to same-sex couples points to the conclusion that there is no rational state interest in denying them the rites of marriage as well."
*'''The purpose of marriage is procreation:''' "The obvious natural and social reality is that one does not have to be married to procreate, nor does one have to procreate in order to be married." 

Kramer, a Catholic Republican Judge appointed by Pete Wilson, California's previous conservative governor, issued a "stay" on his order, making it a tentative decision by delaying its implementation for 60 days to allow the same-sex marriage opponents time to file an appeal to his ruling. The case is widely expected to be brought before the California Supreme Court.

Less than a year ago, the state's Supreme Court annulled more than 4,000 same-sex marriages which took place in San Francisco County in 2004. The court did not rule on the constitutionality of same-sex marriages, but ruled more narrowly that San Francisco mayor Gavin Newsom overstepped his authority by unilaterally deciding not to follow state laws he did not agree with instead of challenging the laws in court, which is the proper legal way to overturn or affirm laws in California and much of the United States.