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.
Federal government of the United States
One of the theoretical pillars of the U.S. Constitution is the idea of "checks and balances" among the powers and responsibilities of the three branches of American government: the executive, the legislative, and the judiciary. For example, while the legislative branch (Congress) has the power to create law, the executive branch under the president can veto any legislation—an act which, in turn, can be overridden by Congress. The president nominates judges to the nation's highest judiciary authority, the Supreme Court, but those nominees must be approved by Congress. The Supreme Court, in turn, can invalidate unconstitutional laws passed by the Congress. These and other examples are examined in more detail in the text below.