A gay rights group has filed a federal lawsuit today against the governor of Nevada, Republican Brian Sandoval, in a bid to extend marriage rights to same-sex couples in the state.

The lawsuit has been filed by Lambda Legal Defense and Education Fund, claiming that eight gay couples are subject to discrimination as they are unable to marry in the state. Tara Borelli, a lawyer for the firm said that the 2009 domestic partnership law “sends a message that their families are not worthy of equal dignity and respect.”

Nevada banned non-heterosexual weddings through a ballot measure in 2002. The domestic partnership law of 2009 was vetoed by the then Republican governor, Jim Gibbons, but was overridden by the state’s Assembly and Senate.

The lead plaintiffs in the case are Beverly Sevcik (73) and Mary Baranovich (76), who have been together for 41 years, with three children and four grandchildren. “After four decades of sharing a life together, all we want is to commemorate our love for each other in the same way as other couples, through marriage,” Ms Sevcik said in the lawsuit.

The couple, along with three other plaintiffs in the suit, attempted to obtain marriage licenses in the state, but were refused on the grounds of their gender. The remaining four couples obtained their marriage licenses in states where same-sex weddings are legally recognised, though these continue to go unrecognised in Nevada itself.

The lawsuit adds that the couples have been subject to discrimination by hospital officials, police officers, and other government institutions. It says that domestic partnership “lacks the same reputation, standing in the community, and traditions and prestige as marriage.” This deprives the couples and their children of equal dignity and security, it further said.

According to the latest Census figures, the number of gay and lesbian households in Nevada has climbed by 87% from 2000 to 2010, with at least a quarter of those couples raising children. The data suggests that almost 4,600 homes in the state were headed by lesbian couples, while 4,724 were those of gay male couples. Ten years earlier, the total figure, representing all same-sex couples, stood below 5,000.