The California Supreme Court upheld Proposition 8 Tuesday, affirming the ban on same-sex marriage that voters approved last year.

While the justices were split 6-1 regarding the constitutionality of the proposition — which was passed with a 52 percent vote in November’s election — they unanimously agreed that the marriages of as many as 18,000 same-sex couples will be recognized under state law.

In the majority decision, Chief Justice Ronald M. George wrote that because same-sex couples still have the right to civil unions, Prop 8 did “not entirely repeal or abrogate” their right to “choose one’s life partner and enter with that person into a committed, officially recognized and protected family relationship that enjoys all of the constitutionally based incidents of marriage.”

Rather, George wrote, voters chose to reserve the “official designation of the term ‘marriage’ for the union of opposite-sex couples as a matter of state constitutional law.”

In addition to rejecting arguments that Prop 8 was an illegal constitutional revision, the court also denied contentions that the proposition unconstitutionally affected an inalienable right.

While justices said it was “inappropriate” to decide whether or not same-sex marriages performed outside California would be recognized by the state, they voted to uphold existing California marriages that took place before Prop 8 was passed. 

“The marriages of same-sex couples performed prior to the effective date of Proposition 8 remain valid and must continue to be recognized in this state,” George wrote.

Despite this decision, protests broke out in cities across the state — including San Francisco and Los Angeles — as opponents of Prop 8 expressed their dismay that the decision was upheld.

At USC, however, many students said they were not surprised by the decision.

“It’s never a good thing to hear that you’ve had your rights taken away from you, but it honestly was less of a surprise after the whole Prop 8 thing,” said Chris Dunford, one of the founders of the Equal Marriage Rights Initiative at USC, a new organization founded on campus after Prop 8 was approved.

Genevieve Flores, executive director of USC’s Gay Lesbian Bisexual Transgender Assembly, said while she was not surprised by the ruling, she had hoped the court would intervene.

“Honestly, the Supreme Court should have stepped in,” Flores said. “It’s usually up to the Supreme Court to uphold the rights of minorities.”

In a statement from USC College Republicans, Director of Public Relations Lauren Korbatov said while group members had different political opinions regarding Prop 8, the organization agreed with the legal decision made by the court.

“The California Supreme Court ruled today that Proposition 8 was a legal constitutional amendment passed by California voters, and we agree with the legal merits of this assessment,” the statement said. “Our membership has diverse views on the political debate surrounding Proposition 8, and we therefore do not endorse a position on the political aspects of the controversy.”

Political experts said the future of Prop 8 is still unclear, as many opponents have vowed to again present the proposition to voters again — including in the upcoming 2010 election.

Flores agreed, saying it was up to voters to repeal Prop 8.

“The ball’s back in our court,” Flores said.