This chapter evaluates the differences–and surprising similarities–between financial regulation, which does not count as “hard” law and international law, which does count as hard law. As it turns out, though, both depend on domestic institutions to enforce their rules, both institutions are negotiated and iterative, rather than fixed and stable, and both are best at facilitating mutually beneficial cooperation, rather than resolving zero sum disputes.Understanding how international financial regulation achieves its legitimacy through a series of domestic processes, rather than an international one gleaned from state practice and treaty commitments, provides a perspective on public international law.