The Federal Republic of Nigeria is governed in accordance with the provisions of the 1999 Constitution. The Constitution affirms that Nigeria is one indivisible and indissoluble sovereign state, whose constituent units are bound together by a Federal arrangement. It provides for a presidential system of government in which there is an Executive, a Legislature and a Judiciary, with each acting as a check and balance on the powers of the other two arms. The Constitution further provides for the operation of three tiers of government, at the Federal, State and Local levels. These provisions are binding on all authorities and persons throughout the Federation.