The argument against Proposition 8 — result due in a few hours.

Today, the California Supreme Court announces its decision on Proposition 8, the voter initiative passed in November that outlawed same-sex marriage. In May 2008, the court, held that prohibiting same-sex marriages violated the Equal Protection Clause in California’s Constitution.

The briefs filed in the case are all available here.

The essence of the argument advanced against proposition 8, as I understand it, is as follows: the state constitution’s requirement of equal protection requires that same-sex couples be permitted to marry. The state Supreme Court is the final arbiter of the meaning of the state consitution. Thus, a voter initiative that by a mere majority declares that same-sex couples are not permitted to marry usurps the constitutional role of the state supreme court in interpreting the state’s equal protection clause. It’s an interesting argument — if the voters want someone other than the Supreme Court to interpret the state constitution, they must revise the constitution to alter the role of the Supreme Court. Leaving interpretation of constitutions, however, has been firmly embedded in U.S. jurisprudence since Marbury v. Madison, in which, of course, Chief Justice John Marshall stated:

It is emphatically the province and duty of the judicial department to say what the law is. . . . If two laws conflict with each other, the courts must decide on the operation of each.

Thus, the argument in California goes, the electorate usurped the role of the state Supreme Court in voting by a majority that the equal protection clause does not allow same sex marriage. Here, in summary, is the way the argument was articulated by the Petitioners in their Petition for Writ of Mandate (pdf):

13. Proposition 8 alters Article 1 of the California Constitution by adding “SEC. 7.5. Only marriage between a man and a woman is valid or recognized in California.” By its terms, Proposition 8 purports to strip a constitutionally protected minority group of the fundamental right to marry even though that right was previously conferred by the equal protection clause of the California Constitution.

14. Proposition 8 is invalid under the California Constitution because the initiative power does not permit voters to divest a politically unpopular group of rights conferred by the equal protection clause. A transfer of the final authority to enforce the equal protection clause from the judiciary to a political majority can only occur by revision. The Constitution, however, has never been revised to remove final autohority to enforce the equal protection clause from the judiciary.