Gay rights groups have urged the Wisconsin Supreme Court to reject a challenge to the state's gay-inclusive domestic partnership registry, Wisconsin Radio Network reported.

The group Wisconsin Family Action (WFA) and the Christian-based Alliance Defense Fund (ADF) have asked the state Supreme Court to strike down the law, arguing that it is prohibited by the state's constitutional ban on gay marriage approved by voters in 2006. WFA supported the passage of the anti-gay marriage amendment as the Family Research Institute.

Despite being challenged, the law that gives gay and lesbian couples access to 43 rights, most of which center around estate planning and hospital visitation issues, took effect last month.

In briefs submitted by lawyers on Tuesday, gay rights groups Lambda Legal and Fair Wisconsin urged the court to reject the challenge. It takes four justices to agree for the court to accept a challenge.

“The suggestion in this lawsuit that this is substantially similar to marriage is, in our view, simply not credible,” Christopher Clark, senior staff attorney with Lambda Legal, said.

Statistics compiled by the Department of Health show that 970 couples have been added to the registry since its opening.

Governor Jim Doyle created the registry when he added the legislation to the state's budget approved by lawmakers. The state is being represented by Madison attorney Lester Pines, who was hired after Attorney General John Byron “J.B.” Van Hollen refused to defend the law, calling it unconstitutional.