separation of powers
The doctrine that the liberty of the individual is secure only if the three primary functions of the state (legislative, executive, and judicial) are exercised by distinct and independent organs. It was propounded by Montesquieu (De l'Esprit des Lois, 1748), who regarded it as a feature of the UK constitution. In fact, however, while the judiciary is largely independent, the legislature and the executive depend on one another and their members overlap. The doctrine had a great influence over the form adopted for the constitution of the USA and many other countries.