 A recurring concern was tensions between federalism and conceptions of sovereignty. Samuel Pufendorf (1632–1684) maintained that sovereign states could at most “agree to intertwine for all time” in a confederation deciding by unanimity. Move to majority rule turned the legal order into an ‘irregular system’ closer to a state. If sovereignty is a unique site of final and independent authority, federations are no more than voluntary treaties among fundamentally independent states, argued Emmerik Vattel (1714–1767). Later thinkers challenged this understanding of sovereignty, in debates continuing to this day concerning the European Union. (MacCormick 1999, Schütze 2009).