There are currently only three states in the US which have same-sex marriage bans unchallenged in court.

Five gay and lesbian couples in the US state of Alaska filed a lawsuit on Monday challenging the state’s ban on same-sex marriage, leaving only three states with unchallenged bans.

The number will reportedly soon fall to two, as the Washington Post reports that a lawsuit is set to be filed in South Dakota any day.

Nancy Robrahn, 68, and Jennie Rosenkranz, 72, have been together for 27 years. They plan to marry in the state of Minnesota, before coming back to South Dakota to challenge its ban on equal marriage, and recognising same-sex marriages.

Montana, and North Dakota will be the only two states with same-sex marriage bans without lawsuits challenging them.

Arkansas couples have already begun to wed since a ruling on Friday striking down that state’s ban. Over 300 couples have received marriage licences despite the ban still being defended.