Six gay and lesbian couples on Wednesday filed a federal lawsuit challenging Ohio's ban on gay marriage.

Plaintiff couples argue that Ohio's 2004 voter-approved constitutional amendment limiting marriage to heterosexual couples violates the equal protection clause of the 14th Amendment of the U.S. Constitution.

Since December, federal judges have struck down all or part of similar bans in Utah, Oklahoma, Michigan, Texas, Virginia, Ohio, Tennessee and Kentucky.

“A consensus is finally emerging: the Constitution protects the right of consenting adults to love whoever they want,” the lawsuit states. “It is time for Ohio to do the same.”

Jennifer Branch of the Cincinnati-based law firm Gerhardstein & Branch is representing the couples. The firm's partner, Al Gerhardstein, won a recent ruling forcing Ohio to recognize the out-of-state marriages of gay couples.

Attorney General Mike DeWine, who is appealing the marriage recognition suit, told The Enquirer he will also fight Wednesday's broader lawsuit.

“We are going to do what we have to do,” DeWine said. “This would appear to be an incremental strategy. They started with the death certificate, then the birth certificate. Now we're moving to the whole thing. It's not unusual.”

Multiple sclerosis hampers lead plaintiff Michelle Gibson's ability to travel to another state to marry. She and partner Deb Meem have been together for 20 years.

“As I get more and more disabled, I start to think about what I want to leave in the world, what kind of legacy I want to leave,” Gibson said. “This allows me to put something out into the world, to sort of say, 'We're in love. We deserve to have that love recognized, and our families recognized in the world in the same way that any other family would be recognized.'”

Gary Goodman proposed marriage in 2011 to his partner Karl Rece Jr. at a local amusement park's annual Gay Pride night, where the men had met 10 years earlier. (Video of the proposal is embedded on this page. Visit our video library for more videos.)

“We've been together for 13 years, and we would like to be married here in Cincinnati with our friends and family,” Goodman told The Enquirer. “What it boils down to is that in life, sometimes you have to step up and fight for your rights. For us, this is the time.”

U.S. District Judge Michael Barrett has been assigned the case. Barrett, the former chairman of the Hamilton County Republican Party, was appointed to the court by then-President George W. Bush.