Full edition for public use. Constitutions contain the most important rules of our political systems and Constitutional Courts are the most powerful judicial institutions of European states. They are the guardians of the Constitutions and ensure, for instance, the respect for fundamental rights. Since the 20th century their importance is ever growing, which attracted a lot of interest from academia and beyond. Yet, despite numerous investigations, we know little about how and to what extent different Constitutional Courts cite each other. The dataset at hand informs about the number of citations per year across national European constitutional courts, the European Court of Human Rights as well as the European Court of Justice. The respective dataset is relational and measures how frequently and when a specific court cites another court as well as how frequently and when a specific court gets cited by another court.