"Palatino-Roman" The moon, the stepping-stone to exploring the unknown of outer space, is an extremely hostile environment without an atmosphere and climate comparable to that of Earth. Despite such forbidding characteristics, however, the moon has recently attracted attention as China, the ESA, NASA, and even commercial enterprises plan missions to the moon in the near future. This new race to the moon could be a source of future conflict, but the moon is not devoid of legality. The Moon Treaty entered into force with five member states on December 1, 1984. However, as of January 1, 2004, only ten states have ratified the treaty which has been interpreted as placing a moratorium on any lunar exploitation. Although the comparable Antarctic Treaty has had a limited number of members, its impact has nevertheless been considerable. Also, a number of international agreements have developed under the auspices of the Moon Treaty's predecessor, the comprehensive Outer Space Treaty. These agreements have all contributed to the establishment and strengthening of international space law. However, the controversial Moon Treaty is considered to have future effects on the political, economic, and security interests of the international community as a whole by encompassing the Common Heritage of Mankind principle. The purpose of this study is to investigate the low level of ratification of the Moon Treaty and to examine whether and to what extent the parent Outer Space Treaty, the Moon Treaty, subsequent U.N. resolutions, bilateral treaties, and unilateral actions can create, together or independently, a legal regime for the moon that could be claimed to be valid erga omnes, applicable to all. Thestudy thus includes a general discussion of the provisions, rules, and norms of international law. Although the pacta tertiis rule which only binds nations with their consent is undoubtedly recognized as a basic rule of international law, there exist exceptions or qualifications to that rule with respect to the Moon Treaty, and in this case pacta tertiis might not be as strict as once believed. It is argued that certain provisions found in the Moon Treaty are expressions of customary law or have acquired customary law status since they have been recognized and accepted by the international community. Therefore, the study contains a detailed analysis of the Moon Treaty including content textual analysis and recourse to its travaux priparatoires. Emphasis is also placed on provisions of similar treaties for hostile environments such as the Antarctic Treaty and the Convention on the Law of the Sea. Since the Moon Treaty is not the sole source of law relating to the international commons, it has been necessary to examine to what extent these and other legal instruments may be relevant for the creation of customary international law for the moon. The existence of these somewhat overlapping and sometimes colliding legal systems is the nucleus of this work.