Gay and lesbian couples in Arizona have filed a lawsuit to challenge the state’s ban on same-sex marriage.

Seven same-sex couples, and two people whose same-sex partners have died, are involved in the lawsuit, which argues the state’s ban on same-sex marriage is unconstitutional.

Jennifer Pizer, one of the attorneys representing the couple, said in a statement: “Every day that same-sex couples in Arizona are denied marriage, the government sends a message that their families are not worthy of equal dignity and respect”.

Karen Bailey and Nelda Majors, 74 and 74, are the lead plaintiffs in the case. The couple, who live in Scottsdale, Arizona, have been together for 55 years and have raised two children together.

The suit, which was filed at the US District Court in Phoenix today, is the latest in a spate of legal challenges to same-sex marriage bans that have sprung up across the US, after the Defence of Marriage Act was declared unconstitutional last July.

Currently 17 states and the District of Columbia allow same-sex marriages, while UtahOklahomaVirginia and Texas have had bans struck down, pending appeal.

There are currently 51 separate court cases in 28 states pertaining to same-sex marriage.

Kentucky has been ordered to recognise same-sex marriages from other states by March 20, but earlier today the governor hired his own legal team to appeal the ruling.