Over the objections of four dissenters, the court turned away a state constitutional challenge to Washington's marriage law. Here's a summary of the holding from the opinion itself:

In brief, unless a law is a grant of positive favoritism to a minority class, we apply the same constitutional analysis under the state constitution's privileges and immunities clause that is applied under the federal constitution's equal protection clause. DOMA does not grant a privilege or immunity to a favored minority class, and we accordingly apply the federal analysis. The plaintiffs have not established that they are members of a suspect class or that they have a fundamental right to marriage that includes the right to marry a person of the same sex. Therefore, we apply the highly deferential rational basis standard of review to the legislature's decision that only opposite-sex couples are entitled to civil marriage in this state. Under this standard, DOMA is constitutional because the legislature was entitled to believe that limiting marriage to opposite-sex couples furthers procreation, essential to survival of the human race, and furthers the well-being of children by encouraging families where children are reared in homes headed by the children's biological parents. Allowing same-sex couples to marry does not, in the legislature's view, further these purposes.2 Accordingly, there is no violation of the privileges and immunities clause.

There also is no violation of the state due process clause. DOMA bears a reasonable relationship to legitimate state interests -- procreation and child-rearing. Nor do we find DOMA invalid as a violation of privacy interests protected by article I, section 7 of the Washington State Constitution. The people of Washington have not had in the past nor, at this time, are they entitled to an expectation that they may choose to marry a person of the same sex.

Finally, DOMA does not violate the state constitution's equal rights amendment because that provision prohibits laws that render benefits to or restrict or deny rights of one sex. DOMA treats both sexes the same; neither a man nor a woman may marry a person of the same sex.