This article studies the normative activity developed by the Security Council (SC) in recent years, particularly in the fight against terrorism. This legislative activity has aroused a great deal of controversy both among scholars and the States. Is the SC acting ultra vires? Has it revealed a new form of creating of international norms, which overrides definitively States' consent as the only material source of international law? This contribution tries to answer these questions by investigating the scope of the SC powers in the Charter, their historical background and the reaction of UN Member States towards its Resolutions. After this analysis, it is submitted that the SC does have a legislative capacity, but with important legal, political and practical limits.