This thesis explores the use of chemical weapons in Syria in its complexity, and further investigates its legality from the point of view of international law, assessing the prohibitory provisions of international treaty law, international customary law and other legal documents relevant for the protection of human rights. Departing from a supposedly effective legal framework designed to criminalize and prevent the use of chemical weapons as a violation of both these legal norms and human rights standards, the impunity surrounding their repetitive emergence in Syria strikes and the question why the existing regulations fail to achieve their ultimate goal arises. In order to explain this contradiction, a further analysis of the geopolitical dimension of the conflict is made, with references to the interests of major foreign powers, US and Russia, arguing that the geopolitical factor in fact helps to understand the failure of international law to prevent the emergence of chemical weapons in Syria.