Separation of powers is often regarded as a second limb functioning alongside the rule of law to curb the powers of the government. In many modern nation states, power is divided and vested into three branches of government: The legislature, the executive, and the judiciary are known as the horizontal separation of powers. The first and the second are harmonised in traditional Westminster system.W B Gwyn, The Meaning of the Separation of Powers: An Analysis of the Doctrine From Its Origin to the Adoption of the United States Constitution, Tulane University (1965). Vertical separation of powers is decentralisation.
