HONOLULU -- A group of supporters for civil unions filed a lawsuit against Gov. Linda Lingle on Thursday.

The complaint filed in circuit court by the American Civil Liberties Union of Hawaii and Lambda Legal argues that the state violates the constitution by denying same sex couples the rights and protections currently available to heterosexual couples through marriage.

"The courts exist to ensure that everyone has the same basic rights, whether they are the majority or whether they are a small minority like lesbian and gay families, like the families standing here today," said Jennifer Pizer, Lambda Legal senior counsel.

The lawsuit was filed on behalf of six same-sex couples, five from Oahu and one from the Big Island.

The lawsuit does not ask for marriage status, only for the state to grant the full range of equal protections under the law to gay and lesbian couples.

The plaintiffs said this lawsuit is unique because the state has already acknowledged there is some discrimination against same sex couples with the reciprocal benefits system.

Now they said it will be up to the state to prove why it's providing just some benefits to same sex couples and not all the same benefits married couples are allowed.

Plaintiffs Robie Lovinger, 56, and Louise Esselstyn, 65, have been together for 17 years. Esselstyn suffers from multiple sclerosis and is worried they could lose their home if Esselstyn needs nursing home care in the future and the state demands repayment of medicaid costs in ways not required of married spouses.

Which is why, despite the added stress of a lawsuit, they're willing to take on the fight for civil unions.

"Between the two of us, we are well over 110 years old and it would bring us great joy on that level. On an emotional level, it would be very joyful to have equality," said Lovinger.

Sharing in the fight are co-plaintiffs and friends Danny Robinson, 56, and Allen Castro, 60, from Hilo. Together since 1976, the two said they want to be recognized as a devoted and legitimate family.

"Although we are a family for 35 years, it means a little bit more when the state says you are," said Castro.

The governor announced her veto of the bill earlier this month.

Lingle said she felt that the rights offered by the bill are the same as marriage, but just by another name.

"Gov. Lingle single-handedly vetoed the Legislature's attempt to bring social justice to Hawaii, so pursuing a judicial path is a prudent choice," Equality Hawaii Co-Chair Valerie Smith said.

The lawsuit could take months and possibly years to work its way through the legal system.

Nine states and the District of Columbia offer domestic partnerships, civil unions or same-sex marriages.

No one from the governor's office was available to comment on the lawsuit and the state attorney general's office said it hadn't had time to review the suit.