The Wisconsin Club for Growth is suing to stop a state investigation of the 2011 and 2012 recall elections, according to the Milwaukee Journal Sentinel.

The conservative group and its treasurer, Eric O’Keefe, filed a lawsuit Monday in federal court against the state judge and several prosecutors involved in the secret probe, known as a “John Doe” investigation. According to the Journal Sentinel, the lawsuit claims the investigation violates the Wisconsin Club for Growth’s rights to free speech, free assembly, and equal protection under the law. It asks the court to block prosecutors from continuing with the probe, and free the Wisconsin Club for Growth from having to cooperate.

The John Doe investigation currently underway grew out of an earlier John Doe that snared six former aides and associates of Gov. Scott Walker (R). According to the Journal Sentinel, the latest John Doe is looking at whether groups like Wisconsin Club for Growth coordinated illegally with Republican candidates during the recent recall elections in the state.

The Wisconsin Club for Growth’s lawsuit contends that the initial John Doe investigation “grew into an ongoing audit of the Walker campaigns, allowing prosecutors an inside track to scrutinize actions of Walker staffers as they were taken, despite that they were unrelated to the original purported purpose of the investigation.” John Doe investigations allow prosecutors to require people to give testimony, and often involve gag orders.

The newly filed lawsuit comes a few weeks after the current John Doe investigation hit roadblock. Reserve Judge Gregory Peterson, who is overseeing the probe, issued a secret order quashing subpoenas against conservative groups that supported Walker, according to the Journal Sentinel.