The rule of law applies to the United Nations and should guide all its activities. As promising as this key statement of the United Nations General Assembly Resolution 67/1 may sound, its meaning is not entirely clear. How is the rule of law to be defined, and what is its legal basis at the international level? What does the rule of law mean for the different activities of the United Nations with external effects such as sanctions, peacekeeping and development, what for its internal administration and justice system? The conference on the Rule of Law and Its Application to the United Nations held at the Max Planck Institute Luxembourg on 11–12 September 2014 addressed these questions inter alia and took a comprehensive look at Resolution 67/1. The conference provided both the academic perspective and the reality of practice due to the participation of various practitioners and United Nations officials.