Alaska's ban on same-sex marriage was officially challenged Monday when five gay couples filed a lawsuit to declare the ban unconstitutional.

The plaintiffs in the suit, which was filed in Anchorage's federal court, are four couples who were married outside of Alaska and one unmarried couple. The plaintiffs claim that the ban on gay marriage violates their right to due process and equal protection under the law, The Associated Press reported.

The suit aims to declare the same-sex marriage ban in Alaska unconstitutional, as well as ban state laws that do not recognize gay marriages that were performed in other states or countries.

In 1998, Alaska approved a constitutional amendment through a referendum vote that outlaws gay marriage, defining marriage as solely between one man and one woman.

The tide started to change last year when the U.S. Supreme Court struck down the part of the Defense of Marriage Act that prevents same-sex couples from having the same federal benefits as straight couples. Federal courts have also struck down bans in a few states, including Hawaii and Illinois.

Attorney Heather Gardner said that under Alaska's state law, "A couple who marries in Seattle and returns home to Alaska are married in the eyes of the law when their plane lifts off from SeaTac (airport) but are legal strangers when the flight touches down in Alaska."

The plaintiffs in the case are Christina LaBorde and Susan Tow; Sean Egan and David Robinson; Katrina Cortez and Tracey Wiese; Courtney Lamb and Stephanie Pearson; and Matthew Hamby and Christopher Shelden. Out of the four couples, Lamb and Pearson are not married.

Hamby said he and his husband, who were married in Canada in 2008, are helping file the lawsuit "because marriage should be available to all loving couples. It's important to us that our family is recognized by the State of Alaska and that we have the same rights and privileges as others."

The defendants in the case are Gov. Sean Parnell and Attorney General Michael Geraghty. Geraghty has said that he will continue to defend the prohibition of same-sex marriage in the state.

Geraghty said he will not make any decision based on a federal court ruling that must still be reviewed.

"Would everybody vote the same way today? Who knows? But it's on the books," Geraghty said in Februrary.

"Eventually, as I said, one day there will be guidance," he continued. "I'm sure one day there will be a decision one way or the other. And when that happens, obviously we will comply with the decision."

A proposal was introduced to stop the same-sex marriage ban in Alaska during the last congressional session, but it did not move forward.