Our article examines the practice of third-party amicus participation before international criminal tribunals (ICTS) and considers its impact on the efficiency and legitimacy of the international criminal process. Our review focuses on the provenance of third-party interventions, their nature and their impact (if any) on the reasoning of the ICT in a given case. We note that a significant proportion of the amicus submissions are from western non-governmental organizations and individuals, rather than from the communities most directly affected by the work of ICTS. We consider the implications of this finding in the context of the well-documented ‘image problems’ that plague ICTS. We find that ICTS tend to manage the participation of third-party amici fairly judiciously, and conclude with some suggestions regarding how the engagement between ICTS and amici could be improved to enhance both the efficiency and the legitimacy of international criminal proceedings.