In a time where the international community seems unable or unwilling to commit to binding instruments to solve global-governance issues, ranging from climate to cybercrime, increased reliance on customary norms presents a path forward. Using the case of space traffic, this author investigates if and how customary international law can emerge to govern complex transnational issues. The traditional approach to international custom is augmented with perspectives from the broader field of social science to accord for the influence of private actors and technological development on the formation of customary law.

Commercialization of the space sector has unleashed a tremendous proliferation of satellites in the orbits of Earth. Without globally aligned “rules of the road” for the orbital highways, the collective human space activities are on an unsustainable path towards congestion, competition, and rapidly increasing collision risk. In lieu of an elusive treaty solution, binding rules of the road for space may emerge through customary international law.