Military activity in space

Article IV of the Outer Space Treaty prohibits signatories from placing weapons of mass destruction in space or testing weapons or military manoeuvres on celestial bodies (e.g., planets, moons, asteroids, etc.). It also establishes that the Moon and celestial bodies shall be exclusively used for peaceful purposes.

The Outer Space Treaty does not, however, explicitly ban the use of conventional weapons in space. As such, legal scholarship suggests the deployment of conventional weapons in Earth’s orbit may be consistent with international space law, the law of armed conflict, and the UN Charter.

Article III of the Outer Space Treaty also states that signatories “shall carry on activities in the exploration and use of outer space, including the Moon and other celestial bodies, in accordance with international law, including the Charter of the United Nations.” Accordingly, Article 2(4) of the UN Charter will apply respect to military activities in space, meaning that parties are prohibited from the threat or use of force against the territorial integrity or political independence of any state in the context of space-related activities.

There are, however, two exceptions to Article 2(4) of the Charter, which can both be found in Chapter VII. The first exception, found in Article 42, allows the UN Security Council to authorize military action to maintain or restore international peace and security. The second exception, Article 51, allows states to use military force in self-defence.

Also authoritative on the subject matter, Article 38 of the Statute of International Court of Justice states that international law may be shaped by conventions and customs generally accepted as law. Thus, customary international law is derived from the normative expectations developed through observation of the actions of state actors in the international system.

Up to this point in history, space exploration has been rare, and the pursuit of just a handful of nations. As more nations begin exploring, commercializing, and militarizing outer space, one should expect new norms regarding space exploration to emerge. And thus, new customary laws. 

What law governs the Moon? ->