Niels Petersen is a Senior Research Fellow at the Max Planck Institute for Research on Collective Goods. His main areas of research are international law, comparative constitutional law and constitutional theory. He holds a PhD. in law from the University of Frankfurt and an M.A. in Quantitative Methods in the Social Sciences from Columbia University. He worked as a legal advisor for the GIZ Legal Advisory Service in Beijing in 2005/06. Furthermore, he was a Visiting Professor at the Hertie School of Governance in Berlin in spring 2012 and an Emile Noel Fellow at the New York University School of Law during the 2012/13 academic year. He is currently working on a book project on the application of the proportionality principle by the German Constitutional Court, the Canadian Supreme Court, and the South African Constitutional Court. His most important publications are Avoiding the Common Wisdom Fallacy: The Role of Social Sciences in Constitutional Adjudication (International Journal of Constitutional Law 11/2, 2013), Determining the Domestic Effect of International Law through the Prism of Legitimacy (Heidelberg Journal of International Law 72/2, 2012), and The Principle of Democratic Teleology in International Law (Brooklyn Journal of International Law 34/1, 2008).