This chapter describes the broad challenges involved in establishing global order under conditions of anarchy through international law. The fact that there is no world government with powers akin to national governments means that maintaining cooperative relations between and among states is always a careful balancing act, given the problem of enforcing international law in the absence of a single, overarching sovereign authority. The chapter looks at law in the global sphere through the notion of rule of law. It then considers the emergence of international law in broad historical perspective. Moving on to international law in the twentieth century, and up to the present period, the chapter examines the nature of treaties, charters, and covenants which operate in multiple issue areas from postal services, trade, and aviation to communications, the environment, and human rights. It also focuses on two major international courts: the International Court of Justice (ICJ) and the International Criminal Court (ICC). Finally, the chapter reflects on how the principles and practices of a rules-based international order are faring in the contemporary period with a focus on Russia, China, and the US.