By Peter Henderson and Dan Levine 

SAN FRANCISCO (Reuters) - Looking for clues about the upcoming U.S. Supreme Court vote on gay marriage? Check out California's past.

Five years ago, the California high court was divided along similar lines as the U.S. court is today: a single justice was considered the likely swing vote on the constitutionality of gay marriage.

As it turns out, the two justices casting those deciding votes share similar political backgrounds, judicial philosophy and even personal style, raising the possibility they might reach the same conclusion about gay marriage. The California court endorsed it without reservation.

U.S. Supreme Court Justice Anthony Kennedy, 76, and retired California Supreme Court Chief Justice Ron George, 73, both grew up in post-war California, Kennedy in the northern, somewhat provincial state capital Sacramento and George in southern California's Beverly Hills.

They both thrived under Ronald Reagan, who as governor in 1972 appointed George to his first Los Angeles court post and in 1987, as president, nominated Kennedy to the U.S. high court.

Former California Supreme Court Justice Carlos Moreno, a member of the court who voted in favor of gay marriage, remembers George being "deeply concerned" about reaching the right conclusion on the case in 2008.

"It is sort of like Justice Kennedy," Moreno said in a recent interview. "Is Kennedy going to write this U.S. Supreme Court opinion for history?"

George declined to comment on the upcoming Supreme Court oral argument.

Kennedy and George are friends but not close ones, say acquaintances who describe both as gracious, thoughtful men.

"They were cut from the same cloth, it was a generational difference from how people are today - growth-oriented, conservative, but egalitarian, the society that made California the way it is today," recalled Jonathan Stein, who helped organize a 2011 Beverly Hills Bar Association dinner at which Kennedy presented an award to George. Kennedy rescheduled an event of his own to make it work, Stein said.

'SAME TYPE OF JUDGE'

The issue Kennedy faces began in George's court, which in 2008 ruled that the state constitution provided that gays should be allowed to marry. Less than six months later, California voters passed Proposition 8, adding a ban on gay marriage to the state constitution.

A challenge to Proposition 8, based on the federal Constitution, is one of two cases on gay marriage scheduled for oral arguments before the U.S. Supreme Court on March 26 and 27. The other takes on the federal Defense of Marriage Act, which defines marriage as between opposite-sex couples only.

In both cases, the high court can avoid the question of whether marriage is a fundamental right for gay couples. The justices could strike down Proposition 8 on narrow grounds by finding that the state violated equal protection rights when it took away the title of marriage from same-sex couples, while leaving in place other benefits connected with marriage.

Such a ruling would leave in place gay marriage bans in most other states, although it would cast into doubt laws in seven states that recognize civil unions or domestic partnerships but not gay marriage.

Kennedy is expected to cast the key vote in the Supreme Court, navigating as he frequently does between four conservative and four liberal colleagues. Five years ago, George struggled to balance concerns about discrimination of gays against the credo of judicial restraint.

Before the California court scheduled oral arguments that year, George separately informed each of his six colleagues that he would prepare a draft opinion and consider their feedback, say sources familiar with the events. Such individual meetings are not routine, underscoring the delicacy of the matter.

In another unusual twist, George's long draft contained two possible endings: one ruling for gay marriage and one against, the sources said, making it clear he had not made a final decision. The response from his colleagues revealed that they were split three to three, the sources said. After considering all the arguments George ultimately voted to allow gay marriage.

Kennedy, who has more of a libertarian bent than George does, has written multiple opinions on gay rights which provide a better guide to how he will rule on marriage than any comparison to George, said Erwin Chemerinsky, dean of the University of California, Irvine School of Law.

Key among those is the 2003 case which struck down a Texas anti-sodomy law, Lawrence v. Texas. In it, Kennedy described changing public values and the lens of history.

"Times can blind us to certain truths and later generations can see that laws once thought necessary and proper in fact serve only to oppress," Kennedy wrote.

EVOLUTION

George, in his 2008 opinion, described "the evolution of our state's understanding concerning the equal dignity and respect to which all persons are entitled without regard to their sexual orientation," as a basis for his pro-gay-marriage conclusion.

Whether Kennedy will take the final step as George did, and conclude marriage rights are not bound by sexual orientation, may depend in part on his view of history. A U.S. Supreme Court ruling is expected by the end of June.

Chemerinsky described Kennedy's choice as writing either the next Plessy v. Ferguson, the 1896 case which established the racist standard of "separate but equal," or the gay rights version of Brown v. Board of Education, the 1954 Supreme Court decision that struck down the segregationist doctrine.

Northwestern University law professor Andrew Koppelman, an expert on gay rights law, said Kennedy and the rest of the high court were nervous about "being disgraced in history."

"For that reason, I expect that you are going to get a decision that is fairly modest," he said.

George's decision, and perhaps Kennedy's, may have a more personal angle, though.

Gay marriage began in California when same-sex couples flocked to San Francisco City Hall in 2004, after Mayor Gavin Newsom unilaterally lifted the prohibition on gay marriage.

The justices watched from their ornate offices facing the Civic Center Plaza. "We saw dozens, scores of people getting married and celebrating and signing right outside the City Hall steps," said Moreno. His job was to stay neutral, he said. "At the same time, it is a bit hard to disassociate yourself either from the jubilation or the great disappointment associated with the acts that the court has participated in," he concluded.

Santa Clara University Law School professor Gerald Uelmen, who knows both the former California chief justice and Kennedy, said that the view of the plaza strongly influenced George in his marriage opinion.

"I wouldn't say they are peas in a pod but I think they are the same type of judge. I would classify both of them as pragmatic - as conservative but very much aware of how the law is changing and what role the court should play in that." 

(Additional reporting by Lawrence Hurley)

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