The U.S. Supreme Court is a heavily divided high court with key cases coming down to a 5-4 vote. Kennedy, a native Californian and Reagan appointee, often is that swing vote, and some say he could be the key in deciding same-sex marriage.
"Justice Kennedy specifically has authored the two most important gay and lesbian rights cases," Prof. Larry Levine of the University of the Pacific McGeorge School of Law said.
Levine teaches sexual orientation law and knows Kennedy, who taught at the campus for years and comes back once in a while to visit or lecture. His portrait hangs in the new library.
One Colorado case called "Romer" is similar to Prop 8. It wasn't about same-sex marriage, but an initiative denying gays and lesbian protection from things like job and housing discrimination. Kennedy was clear in saying that was wrong in his 1996 decision.
"Justice Kennedy very powerfully said you cannot under the equal protection clause single out a group and say 'We're going to take away rights, we're going to treat you differently because we don't like you,'" Levine
The attorney for Prop 8 supporters says the Romer case doesn't apply.
"In this case, the people were just exercising their right to re-institute the definition of marriage," Andy Pugno said.
Pugno also wonders whether Prop 8 will really come down to Kennedy.
"Declaring a right to same-sex marriage that could sweep away the marriage laws of most state in the country would be a very radical step and I don't see our Supreme Court doing that," Pugno said.
Of course, all this speculation on Kennedy may be for nothing. The U.S. Supreme Court accepts only 1 percent of the cases each year. The Prop 8 ruling could be considered so narrowly tailored to California that it requires no review.