ANCHORAGE, Alaska >> A federal judge has struck down Alaska’s first-in-the-nation ban on gay marriages.

U.S. District Judge Timothy Burgess on Sunday said the ban violates the U.S. constitutional guarantee of due process and equal protection.

The state could appeal to the 9th Circuit Court, where chances of it winning were slim since the federal appeals court already has ruled against Idaho and Nevada, which made similar arguments.

Five gay couples had asked the state of Alaska to overturn a constitutional amendment approved by voters in 1998 that defined marriage as being between one man and one woman.

The lawsuit filed in May sought to bar enforcement of Alaska’s constitutional ban on same-sex marriage. It also called for barring enforcement of any state laws that refuse to recognize gay marriages legally performed in other states or countries or that prevent unmarried gay couples from marrying.

Alaska voters in 1998 approved a state constitutional amendment defining marriage as being between one man and one woman. But in the past year, the U.S. Supreme Court has struck down a provision of the federal Defense of Marriage Act that prevented legally married same-sex couples from receiving a range of federal benefits. Federal courts also have since struck down state constitutional bans in a number of states.

The plaintiffs are Matthew Hamby and Christopher Shelden; Christina LaBorde and Susan Tow; Sean Egan and David Robinson; Tracey Wiese and Katrina Cortez; and Courtney Lamb and Stephanie Pearson. Lamb and Pearson are unmarried.

Defendants included Gov. Sean Parnell and Attorney General Michael Geraghty, who earlier this year told The Associated Press he would continue to defend the state’s constitutional ban on same-sex marriage, even as federal courts around the country strike down similar bans.

The Alaska Legislature is solidly Republican. GOP leaders in the Alaska House were left apologizing for laughter after a February 2013 news conference when members were asked about same-sex partnerships. Some websites and blogs had cast this as majority members laughing at or laughing off the idea of civil unions.

House Speaker Mike Chenault at the time called the laughter inappropriate but said it was in reaction to which legislator had to field the difficult question.