In an unanimous decision, the Iowa Supreme Court upheld the right of same-sex couples to marry. The court, which was reviewing a district court decision allowing six gay couples to marry, found that “limiting civil marriage to a union between a man and a woman violates the equal protection clause of the Iowa Constitution”:

In a unanimous decision, the Iowa Supreme Court today held that the Iowa statute limiting civil marriage to a union between a man and a woman violates the equal protection clause of the Iowa Constitution.

The decision strikes the language from Iowa Code section 595.2 limiting civil marriage to a man and a woman. It further directs that the remaining statutory language be interpreted and applied in a manner allowing gay and lesbian people full access to the institution of civil marriage.

The ruling “makes Iowa the first Midwestern state, and the fourth nationwide, to allow same-sex marriages.” In the opinion, the judges compared protecting the right to same-sex marriage to past rulings by the Iowa Supreme Court that protected women’s rights and struck down slavery and segregation laws:

So, today, this court again faces an important issue that hinges on our definition of equal protection. This issue comes to us with the same importance as our landmark cases of the past. The same-sex-marriage debate waged in this case is part of a strong national dialogue centered on a fundamental, deep-seated, traditional institution that has excluded, by state action, a particular class of Iowans. This class of people asks a simple and direct question: How can a state premised on the constitutional principle of equal protection justify exclusion of a class of Iowans from civil marriage?

In its opinion, the court addressed concerns that today’s decision would trample on religious views of marriage, writing that “religious doctrine and views contrary to this principle of law are unaffected. “A religious denomination can still define marriage as a union between a man and a woman.”

Richard Socarides, a former senior adviser to President Bill Clinton on gay civil rights, told the Des Moines Register today that the “decision could set the stage for other states.” AmericaBlog’s Joe Sudbay calls the ruling “a huge win for marriage equality,” writing that “more and more Americans support marriage equality and it’s only going to increase.”

Update: Iowa Senate Republican Leader Paul McKinley released a statement calling on the Iowa legislature to "immediately act to pass a Constitutional Amendment that protects traditional marriage, keeps it as a sacred bond only between one man and one woman."

Update: The Des Moines Register said that the ruling makes Iowa the fourth state nationwide to allow same-sex marriages. Massachusetts legalized it in 2003, as did Connecticut in 2008. California's Supreme Court legalized it in May 2008, but Proposition 8 effectively banned it again in Nov. 2008.

Update: Politico's Ben Smith writes of the ruling: "It's really a sweeping, total win for the gay-rights side, rejecting any claim that objections to same-sex marriage can be seen as "rational," rejecting a parallel civil union remedy, and pronouncing same-sex marriages and gay and lesbian couples essentially normal."

Update: Statements on the ruling by Iowa Gov. Chet Culver and Sen. Tom Harkin (D-IA) are here.