Stated by John Locke, the theory of the separation of powers is finalized and comprehensively explained by Montesquieu (Charles-Louis de Secondat, born in 1689) in the famous work “About the spirit of the laws” (1748). He was the one who developed the theoretical construction, which remained a classic, of the separation of powers in the state. That is why it is necessary to look first at the main ideas to be included in this piece of work, which consecrated the author as being the father of the classical theory of the separation of powers in the state. The main differences in Locke and Montesquieu’s conceptions consist in the structure and the status of the branches of state power. Being a supporter of the progressive movement since then, the French thinker Montesquieu has argued for the need to organize political power, based on the principle of separation of powers in the state, starting from the imperative of protecting the person’s freedom, of the citizen.