In eleven chapters, distinguished scholars reflect on how to approach these questions from historical, system-oriented and actor-centered perspectives. The contributions engage with the rise of European international law since the 17th century, the decay of the international rule of law, compliance as an indicator for the state of international law, international law and informal law-making in times of populism, the rule of environmental law and complex problems, human rights in Europe in a hostile environment, the influence of the BRICS states on international law, the impact of non-state actors on international law, international law's contribution to global justice, the contestation of value-based norms and the international rule of law in light of legitimacy claims.