Can data science be used to improve the functioning of courts, and unlock the positive effects of institutions on economic development? In a nationwide randomized experiment in Kenya, we use algorithms to identify the greatest sources of court delay for each court and recommend actions. We randomly assign courts to receive no information, information, or an information and accountability intervention. Information and accountability reduces case duration by 22%. We find an effect on contracting behaviour, with more written labor contracts being signed by firms, and an effect on wage, since jobs with written labor contracts pay more. These results demonstrate a causal relationship between judicial institutions and development outcomes.