BOISE, Idaho -

A federal judge says Idaho's attorney general can intervene in a lawsuit challenging the state's ban on same-sex marriage, even though Gov. C.L. "Butch" Otter is already a party in the case.

U.S. Magistrate Judge Candy W. Dale made the ruling Tuesday, saying that Idaho has a strong interest in defending its laws against constitutional attack and that Idaho Attorney General Lawrence Wasden was in a position to assert those defenses.

The judge acknowledged that at least some of Wasden's defenses will mirror that already being presented by Otter, but said that redundancy alone wasn't enough to keep Wasden out of the case.

Four couples filed the lawsuit challenging Idaho's same-sex marriage ban in November, arguing that the ban violates the U.S. Constitution's equal protection and due process guarantees.