Fond du Lac County was organized judicially in 1844 with the establishment of the Territorial District Court for Fond du Lac County. Administered under the statutes of the Wisconsin Territory, 1839, the district court was given jurisdiction in chancery as well as common law. It was also granted the jurisdiction of the Circuit and District Courts of the United States in matters arising under the Constitution and laws of the United States. The Territorial Legislature further defined the jurisdiction of the district court by granting it original jurisdiction in all actions at law or in equity in which the amount in controversy exceeded $50 and in all cases of treason, felony, crimes, and misdemeanors.
With statehood the Territorial District Courts were superseded by the circuit court system. The State Constitution of 1848 provided for the establishment of a Fourth Judicial Circuit comprised of Fond du Lac County, Brown, Winnebago, Calumet, Manitowoc and Sheboygan counties. Jurisdiction was conferred in all matters, both civil and criminal, within the State not prohibited by the Constitution. The circuit court also has the general power to hear appeals from inferior courts and tribunals.
