The separation of powers or division of powers is a political principle in some forms of government, in which the legislative, executive and judicial powers of the State are exercised by different government bodies, independent and independent of each other. This is the fundamental quality that characterizes democracy.
Montesquieu argued that "every man who has power is inclined to abuse it; He goes until he finds limits. In order that power can not be abused, it is necessary that, by the disposition of things, power detain power. " In this way, the vigilance of the three powers among themselves is entrusted as each one watches, controls and stops the excesses of the others to prevent, by own ambition, that one of them predominates over the others. It can be contrasted with the merger of powers and separation of functions in parliamentary systems, where the executive and the legislature are unified, because the legislature appoints the executive.