A Michigan wedding venue that was investigated for turning away a same-sex couple is now attempting to legalize LGBT discrimination statewide.

The owners of Rouch World, a 300-acre park and wedding venue in Sturgis, are suing the Michigan Department of Civil Rights.

The department launched an investigation into Rouch World after the owners, brothers Jayme and Ben Rouch, turned away a lesbian couple based on their “Christian beliefs.”

Although Michigan law doesn't explicitly prohibit LGBT discrimination, the Department of Civil Rights has interpreted the state's ban on “sex”-related bias to include sexual orientation and gender identity. The department launched its investigation in response to a complaint from the couple, Natalie Johnson and Megan Oswalt.

“Rouch World is asking the court to grant a declaratory judgment saying sexual orientation and gender identity are not covered by the Elliott-Larsen Civil Rights Act and to grant injunctions stopping the investigation into Rouch World and future investigations of discrimination based on sexual orientation and gender identity,” MLive.com reports.

The Rouch brothers are represented David Kallman of Kallman Legal Group, who says his clients were subject to “onerous documentation requests” as part of the investigation.

“Our defense is pretty simple,” Kallman said. “Our Michigan law at least as it currently stands… does not include sexual orientation or gender identity as protected categories.”

The Department of Civil Rights says the state will defend its position.

“We've long expected this action and have said since the time of the Commission's vote that the courts are the right place to ultimately decide the question,” a department spokesperson said in a statement. “We obviously hold a different legal opinion than the individuals who filed suit. The Michigan Attorney General's office will defend our position in court and we continue to believe the courts will decide in our favor.”