Human rights in general and the international human rights system in particular have come under increasing attack in recent years. Quite apart from the domestic and global political events since 2016, including an apparent retreat from international institutions, the human rights system has in recent times come in for severe criticism from academic scholars. Amongst the various criticisms levelled have been: (1) the ineffectiveness and lack of impact of international human rights regimes, (2) the ambiguity and lack of specificity of human rights standards, (3) the weakness of international human rights enforcement mechanisms, and (4) the claim to universalism of human rights standards coupled with the hegemonic imposition of these standards on diverse parts of the world. This article responds to several of those criticisms by introducing the idea of experimentalist governance, interpreting key aspects of the functioning of certain international human rights treaties from the perspective of experimentalist governance theory, and surveying a body of recent scholarship on the effectiveness of such treaties. Contrary to the depiction of international human rights regimes as both ineffective and top-down, the article argues that they function at their best as dynamic, participatory, and iterative systems. Experimentalist governance offers a theory of the causal effectiveness of human rights treaties, brings to light a set of features and interactions that are routinely overlooked in many accounts, and suggests possible avenues for reform of other human rights treaty regimes with a view to making them more effective in practice.