Des Moines, Iowa ? Iowa’s Supreme Court legalized gay marriage Friday in a unanimous and emphatic decision that makes Iowa the third state — and first in the nation’s heartland — to allow same-sex couples to wed.

Iowa joins only Massachusetts and Connecticut in permitting same-sex marriage. For six months last year, California’s high court allowed gay marriage before voters banned it in November.

The Iowa justices upheld a lower-court ruling that rejected a state law restricting marriage to a union between a man and woman.

The county attorney who defended the law said he would not seek a rehearing. The only recourse for opponents appeared to be a constitutional amendment, which could take years to ratify.

“We are firmly convinced the exclusion of gay and lesbian people from the institution of civil marriage does not substantially further any important governmental objective,” the Supreme Court wrote.

Iowa lawmakers have “excluded a historically disfavored class of persons from a supremely important civil institution without a constitutionally sufficient justification.”

To issue any other decision, the justices said, “would be an abdication of our constitutional duty.”

The Iowa attorney general’s office said gay and lesbian couples can seek marriage licenses starting April 24, once the ruling is considered final.

Des Moines attorney Dennis Johnson, who represented gay and lesbian couples, said “this is a great day for civil rights in Iowa.”

At a news conference announcing the decision, he thanked the plaintiffs and said, “Go get married, live happily ever after, live the American dream.”

Plaintiff Kate Varnum, 34, introduced her partner, Trish Varnum, as “my fiance.”

“I never thought I’d be able to say that,” she said, fighting back tears.

Jason Morgan, 38, said he and his partner, Chuck Swaggerty, adopted two sons, confronted the death of Swaggerty’s mother and endured a four-year legal battle as plaintiffs.

“If being together though all of that isn’t love and commitment or isn’t family or marriage, then I don’t know what is,” Morgan said. “We are very happy with the decision today and very proud to live in Iowa.”

In its ruling, the Supreme Court upheld an August 2007 decision by a judge who found that a state law limiting marriage to a man and a woman violates the constitutional rights of equal protection.

The Polk County attorney’s office claimed that Judge Robert Hanson’s ruling violated the separation of powers and said the issue should be left to the Legislature.

The case had been working its way through the courts since 2005, when Lambda Legal, a New York-based gay rights organization, filed a lawsuit on behalf of six gay and lesbian couples in Iowa.

“Today, dreams become reality, families are protected and the Iowa Constitution’s promise of equality and fairness has been fulfilled,” Lambda Legal attorney Camilla Taylor said.

John Logan, a sociology professor at Brown University, said Iowa’s status as a largely rural, Midwest state could enforce an argument that gay marriage is no longer a fringe issue.

“When it was only California and Massachusetts, it could be perceived as extremism on the coasts and not related to core American values.

“But as it extends to states like Iowa, and as attitudes toward gay marriage have evidently changed, then people will look at it as an example of broad acceptance,” Logan said.

Polk County Attorney John Sarcone said his office will not ask for the case to be reconsidered.

“Our Supreme Court has decided it, and they make the decision as to what the law is, and we follow Supreme Court decisions,” Sarcone said.

Gay marriage opponents have no other legal options to appeal the case to the state or federal level because they were not parties to the lawsuit, and there is no federal issue raised in the case, Sarcone said.