The United States is the world’s oldest surviving federation and is a constitutional republic. It is fundamentally structured as a representative democracy.

    The political system of the United States of Americais established on the basis of two principles: the federal system and the “separation of powers”.

    In the American federalist system, citizens are usually subject to three levels of government – federal, state and local. The federal government deals with foreign affairs and matters of general concern to all the states. The states have the basic functions of providing law and order, education, public health and most of the things concerning everyday life. The local governments’ duties are commonly split between country and municipal governments.

    The other principle is the “separation of powers”, which is also called “checks and balances”（制衡）defined by the American Constitution. Under the principle of checks and balances, the federal government is divided into three branches –the legislative, the executive and the judicial. Each branch can check or block the action of the other branches. They are designed in balance and ideally no branch can act to be more powerful than the other two branches.