Wisconsin circuit courts
In addition, the courts are constrained from taking action that will encroach on the powers of the legislative or executive branches. Under the separation of powers doctrine, no branch of government may exercise a power of government assigned exclusively to another branch. The purpose of separating powers among the branches of government is to avoid concentration of governmental power in the hands of a new and to give the various branches the ability to check actions by the other branches.
United States Constitution
Courts established by the Constitution can regulate government under the Constitution, the supreme law of the land. First, they have jurisdiction over actions by an officer of government and state law. Second, federal courts may rule on whether coordinate branches of national government conform to the Constitution. Until the twentieth century, the Supreme Court of the United States may have been the only high tribunal in the world to use a court for constitutional interpretation of fundamental law, others generally depending on their national legislature.