Both democratic legitimacy and the separation of powers as concepts have very much evolved alongside the state and over the last decades the state has been giving up ground to other power holders, particularly international (and even supranational) actors. This brings up the question of whether the combination of these concepts is still viable outside a traditional state context, and if so, in what form? This is the central question the current volume seeks to answer. In 2013 Christoph Möllers published his impressive monograph, The Three Branches; A Comparative Model of Separation of Powers. This inspirational book led to the idea to pitch it against both the agenda of us as researchers of the Institute of Public Law at Leiden Law School (resulting from a 2012 conference) and our own insights, as well as that of fellow travellers in the field.