Summary

The great rise and diversification of the use of outer space raises the question of the limitations to space activities. The ultimate restriction posed by space law is the use of outer space “for peaceful purposes.” Regardless of the semantic approach one adopts with respect to the definition of the term “peaceful purposes” in the text of the Outer Space Treaty, it is the underlying substantive legal normativity which constitutes the determining factor. The applicable international legal rules confirm that the ultimate limit is the prohibition of the use of force laid down in Article 2 (4) of the UN Charter, which applies to outer space along with the exceptions stipulated in the UN Charter and general international law. In addition, the Outer Space Treaty establishes a particular legal regime on celestial bodies, declaring them a demilitarized zone, and bans the stationing of weapons of mass destruction in outer space. Space law, as any other branch of public international law, is of evolutive nature, so future adjustments and developments of its legal normativity in light of the abrupt growth and multiplication of the exploration and uses in the space arena remain open.