The c2d is an academic research center dedicated to the study of direct democratic institutions (referendum and initiative) around the world, their history, legal nature, functioning and political implications. It aims at running an international database, promoting interdisciplinary scientific research, organising conferences and providing services.

The c2d is a department of the Zentrum für Demokratie Aarau (ZDA) and related to the Law School of the University of Zurich.

The team, consisting of political scientists and legal scholars, is located in Aarau, Switzerland.