Prosecuting Politicians for Hate Speech and the Consequences for Democracy is about hate speech trials of politicians, and its effects on citizens. First, it maps 51 cases against 42 political leaders in nine countries since 1965. These leaders include, for instance, Marine Le Pen in France and Geert Wilders in the Netherlands. It theorizes about, and empirically assesses, four effects of these cases: effects on hate crime incidence, on the electoral support for the far right, on democratic support, and on legal system support. Based on partly pre-existing data and partly data the authors have collected, it empirically demonstrates under what circumstances these effects occur and how much uncertainty surrounds their conclusions. The data sources explored in this book include surveys, police reports, experiments, and social media. To analyze this data, the authors use a standard repertoire of statistical models, including advanced times series models. They speak to various academic and societal debates, touching on questions such as: What drives hate crime? How to respond to populists? Does progressive litigation backfire? What fuels far right voting? How to react to hate speech? What causes declines in democratic support? The book's approach is dispassionate, focusing on simply measuring effects of hate speech trials, and it arrives at relatively straightforward (and deeply concerning) findings, arguing that this empirical evidence must be taken into account when deciding to prosecute.