Reuters/Jason Reed
Kennedy, who's notoriously volatile, will likely be the high court's swing vote for the
The other case before the court involves a challenge to Proposition 8, a voter-approved
Gay rights activists are counting on Kennedy's support because he wrote two landmark opinions on gay rights, including one striking down Texas' sodomy law.
The judge who initially struck down Prop 8 as unconstitutional even cited Kennedy's pro-gay opinions 15 times to bolster his argument for marriage equality.
But Kennedy's previous pro-gay opinions don't necessarily reveal how he'll vote in the two cases before the court now, UCLA Law professor Adam Winkler told Business Insider.
Neither pro-gay ruling he wrote involved marriage, and neither would have affected the lion's share of the United States as a decision for gay marriage would.
In Lawrence v. Texas, Kennedy struck down sodomy laws in Texas and 13 other states. His other major pro-gay decision struck down a Colorado law that barred its cities from passing their own laws that protected gays against discrimination.
A "bold ruling" saying there's a constitutional right to gay marriage would strike down the laws in 30 states that have already amended their constitutions to forbid gay marriage, Winkler says.
Kennedy has historically favored states' rights, and he might not issue a decision that would trample on the will of so many states at once.
"I think there are many people in the gay rights community who are fearful that Kennedy is not prepared to say that gay marriage is a constitutional right," Winkler said.