This paper addresses the Common Heritage of Mankind (CHM) with respect to marine and outer space resources, in light of relevant treaties. Possible developments concern internationally, the drafting of a special regulation on the conservation and sustainable use of marine biodiversity of areas beyond national jurisdiction and, nationally, newly-adopted regulations on the commercial use of space resources. CHM’s current role is unclear because of many important political and legal developments. CHM appears to have found new roots in international environmental law and human rights law. However, this approach may not be effective in practice. The paper concludes that while CHM has a great past, its future looks less promising. There are limited prospects of implementation, or of a broadened scope of application. According to some scholars, non-consolidation of CHM in international law is primarily due to the predominance of a ‘legal positivistic’ approach taken by jurists, and the excessive weight accorded to the will of the states in the making of international law. In the author’s view this argument is not entirely convincing, especially if its underlying idea is that further CHM achievements are only possible by drastically changing the fundamentals of international law.