The purpose of this thesis is to determine whether the Security Council has opened a new avenue for law-making at the international level by adopting resolutions under Chapter VII of the UN Charter which create new norms of international law or modify international norms already in force (the normative resolutions). The normative resolutions analyzed in this study pertain to the areas of counterterrorism and the non-proliferation of weapons of mass-destruction. The new approach of the Security Council has been examined in light of the Third World Approaches in International law (TWAIL), as well as from the viewpoint of mainstream lawyers. Furthermore, 15 years of State practice relating to the implementation of these normative resolutions has been studied with a view to determining whether subsequent State practice confirms the exercise of a law-making function by the Security Council. Despite some incremental success in promoting international standards in the fight against terrorism, this thesis illustrates that the Security Council has not succeeded in introducing a new viable form of law-making. The Security Council’s authority to exercise such a function is now under serious doubt and its legitimacy questioned, as its normative resolutions were improperly initiated and adopted under the influence of a Permanent Member of the Security Council. Furthermore, the Security Council’s intervention in areas that are already highly regulated runs the risk of contributing to the fragmentation of international law—a phenomenon that undermines the coherence of international law. Currently, the Council’s normative resolutions are facing serious challenges at the implementation stage and several proceedings before national and regional courts have either directly challenged the normative resolutions, or questioned their enforceability. The Security Council is under continued pressure to further revise its practice or potentially face additional challenges before national, regional, and even international courts which may annul or quash relevant implementing measures. Thus, in light of relevant State practice, it is almost inconceivable that the Security Council would repeat its use of normative resolutions as a means of law-making in the future. Nevertheless, the increasing powers of the United Nations Security Council also stimulates an increasing demand to hold the United Nations accountable for the possible wrongful acts of its principal organ, particularly when its decisions harm individuals. It is argued that in the absence of a compulsory judicial mechanism at the international level, non-compliance with the Council’s decisions is the only viable way to challenge the Security Council wrongful acts. Yet, non-complying State or group of States should clearly identify their actions as countermeasures vis-a-vis ultra vires acts of Security Council and seek support from other like-minded States to avoid being declared recalcitrant, which may be followed by Security Council sanctions.