The paradigms and terms of global governance have raised considerable debates in social sciences, as this elusive notion reflects the complexification of the decision-making fora, actors and processes which address globalised issues. Primarily intended as the legal framework of inter-state relations, international law is deeply shaken up by global governance approaches. In particular, because of systemic regulation and justiciability gaps, it shows a relative inability to create the mechanisms necessary to encompass certain transnational activities which have an important impact while those directly affected often have no direct legal bond with the source-actor which could enable them to ask it directly to account. However, the international scene witnesses the emergence of international grievance mechanisms (IGMs) which escape from traditional legal patterns and might fill certain regulation and justiciability gaps. Though located in an international law context, they are not legal accountability mechanisms and are defined as non-judicial grievance mechanisms set up on a permanent basis by non-binding international instruments or international organizations, which aim at calling an entity –either public or not– to account for its actions when no responsibility/liability mechanism can be set in motion because of the nature of the actors involved, the lack of direct legal bond between them, and the fact the instruments these IGMs control ‘compliance’ with are non-binding. The proposal makes the hypothesis that the study of these mechanisms, which seem symptomatic of international regulation and justiciability gaps, can contribute to the understanding of the mutations international law is experiencing in the context of global governance and beyond, to enhance the knowledge of the challenges ahead in terms of global governance regulation.