Several years ago, a multilateral treaty came into effect among some 45 countries, including most of the major developed countries of the world. The treaty, known as the Outer Space Treaty, forbids any member state from claiming "any planet, satellite, asteroid, or other celestial body" as part of the territory of the member state.
State X, which is not a party to the treaty, recently sent a spacecraft to the Earth's Moon. The crew members of the craft unfurled the flag of State X and claimed a 1,000-square-kilometer surface area of the Moon to be part of the territory of State X. Several small buildings were constructed, including a radio transponder and a landing guidance system.
State Y, joined by the other member states of the Outer Space Treaty, has brought suit against State X in the ICJ. They ask the court to declare that State X's claim to the territorial annexation of part of the Moon be declared void. They argue that the provisions of the Outer Space Treaty forbidding such annexations are part of customary international law and that the treaty itself is an expression of the world community's opinio juris. State X argues that even if there is an opinio juris, none of the members of the world community have acted to prevent the annexation of parts of the surface of the Moon, and therefore there is no usus. How should the court rule? Discuss.