Human rights prosecutions have been the major policy innovation of the late twentieth century designed to address human rights violations. The main justification for such prosecutions is that sanctions are necessary to deter future violations. In this article, we use our new data set on domestic and international human rights prosecutions in 100 transitional countries to explore whether prosecuting human rights violations can decrease repression. We find that human rights prosecutions after transition lead to improvements in human rights protection, and that human rights prosecutions have a deterrence impact beyond the confines of the single country. We also explore the mechanisms through which prosecutions lead to improvements in human rights. We argue that impact of prosecutions is the result of both normative pressures and material punishment and provide support for this argument with a comparison of the impact of prosecutions and truth commissions, which do not involve material punishment.