Three distinct functions

Theorized by Montesquieu in The Spirit of the Laws (1748), this principle distinguishes three main functions within the State:

• The legislative function (legislative power) consists in debating and passing laws. In France, it is exercised by Parliament, which comprises the National Assembly and the Senate.

• The executive function (executive power) consists in conducting public policy and ensuring the enforcement of laws. It falls under the responsibility of the President of the Republic and the Government (led by the Prime Minister) according to their respective powers.

• The judicial function (judicial power or authority) consists in settling disputes, applying the law, and punishing offenses within the jurisdiction of the courts.

A balance, not isolation

The separation of powers does not mean that institutions have no relationship with one another. The Constitution organizes their cooperation and mutual checks and balances: in particular, Parliament oversees the Government's actions (and can bring it down through a vote of no confidence), while the President of the Republic can dissolve the National Assembly.

Preventing arbitrary power

The division of functions and the independence of the judiciary help protect citizens' rights and freedoms. Article 16 of the Declaration of the Rights of Man and of the Citizen of 1789 (DDHC) directly links the guarantee of rights and the separation of powers to the very existence of a Constitution.

Not to be confused

The separation of powers concerns the distribution of the main functions of the State. Decentralization, on the other hand, concerns the transfer of administrative powers from the central State to local authorities (collectivités territoriales — municipalities, departments, regions): this is a different concept.