Experimental Methods in Constitutional Law

Most constitutional law and international human rights scholarship is doctrinal in nature, and if it is empirical, it is mostly qualitative. Less than 2% of the scholarship is quantitative, and only roughly 45% of quantitative research tries to establish causal relationships, of which experimental methods research only comprises about one third. Within research employing experimental methods, 90% are survey experiments. The rest are abstract lab and internet experiments and RCTs. In this Essay, we discuss the role of experiments in constitutional law scholarship and the relative advantage of different experimental methods. We conclude that although there is widespread skepticism about abstract lab experiments, they play a distinctive role in theory development and are complementary to the more widely used vignette or survey experiments.