Rules of the "Space Road:" How Soft Law Principles Interact with Customary International Law for the Regulation of Space Activities

Professor Bin Cheng is credited with the notion that space law, unlike other legal regimes such as air law, can include elements that arise as "instant" customary international law. For Professor Cheng, such customary international law represents an important component of the regulation of outer space exploration and use alongside the United Nations (UN) space treaties, the last of which was concluded more than four decades ago. Although it is true that the UN space treaties codify important principles of customary in­ternational law, it is highly likely that additional customary inter­national law principles have continued to develop in the past forty years. The fact that States have continued to engage in "new" space activities and have demonstrated relatively consistent behavioral practices in specific respects points to a continually evolving body of law. In addition, and perhaps more significantly, the increasing use of so-callep. "soft law" instruments as markers and standard set­ters for various existing and emerging space activities is indicative of an overall consensus on how to engage responsibly and sustain­ably in space. This article examines the development of these soft law instruments and discusses whether, and if so how, some of the more significant guidelines they encapsulate can be regarded as customary international law.