Libya joined the revolutionary wave of demonstrations in the Arab world in 2011. Based on the position that the situation in Libya poses a threat to international peace and security, the Security Council of the United Nations authorized the use of force in its Resolution 1973 (2011), which served as the basis for the coalition of the willing to intervene militarily in Libya. This humanitarian or military intervention, following the concept of Responsibility to Protect, resulted in the overthrow of the 42-year rule by Muammar Gaddafi. The intervention in Libya is analyzed in terms of its legality and its legitimacy. The legality of any military intervention is verified by compliance of acts with international law, which clearly regulates the use of force. The legitimacy of humanitarian intervention is analyzed on the basis of the criterion of just war, and other criteria as developed by many institutions, politicians and experts. The thesis demonstrates that the procedures, which led to the intervention in Libya, were legitimate and legal. However, more questionable was the implementation of the intervention itself, given that a possible arming of the rebels and the overthrow of the Libyan government, among others, raise doubts about the legality and the legitimacy of the intervention and its implementation.