State Auditor Rebecca Otto sued the state of Minnesota and three counties Thursday over a 2015 state law that allows counties to use private audit firms instead of her office.

The suit, filed in Ramsey County District Court, is asking a judge to either preserve her office's "constitutional authority" to audit counties in Minnesota under the new law, or to declare the law unconstitutional. Otto's suit names the state of Minnesota and Becker, Ramsey and Wright counties as defendants.

Forty-seven other counties have also rejected Otto's attempt to audit their books, according to the suit.

"The County Defendants' interpretation of the Privatization Legislation would deprive Minnesota Taxpayers of the auditing oversight and stewardship that the OSA [Office of the State Auditor] has provided for more than 150 years," the suit said. "Such an interpretation would also have a devastating effect on the OSA, including lay-offs, lost talent and experience, a substantially smaller budget, and the loss of primary responsibility of the Office."