The law of armed conflict: Does it apply to space?

When the White House announced earlier this year the creation of Space Force, a new branch of the armed forces, many observers were left scratching their heads. Space technology has undoubtedly come a long way since Neil Armstrong’s lunar escapades in 1969, but the idea of an interstellar infantry still seems to many of us a stretch of the imagination. And yet, outer space and space technology now play a pivotal role in nearly every facet of human life, in a way that was inconceivable even a few decades ago. Weather forecasts, communications technology, navigation systems — all of these rely on space. As we continue to incorporate our thinking about space into the design of new technologies and new avenues for exploration, the possibility of future conflicts involving space rights and resources seems far from abstract.

So, what happens when national defence strategy starts looking to the stars? Does international law follow? As a starting point, the answer appears to be yes. International lawyers categorize outer space as territory comparable to the high seas — a “global commons.” Therefore, the wider body of international law on military conduct applies to outer space, meaning that any space conflict or use of military force in space would be subject to international humanitarian law (e.g. the Geneva Conventions) and the law of armed conflict. In practice, however, it is unclear exactly how these rules translate from one realm to the other.

International law also restricts the use of certain weapons in space, notably in the Outer Space Treaty of 1967, widely regarded as the main agreement on international space law. Article IV of this treaty, for example, explicitly prohibits state parties from placing weapons of mass destruction in orbit around the earth, installing these weapons in outer space, or installing them on celestial bodies (such as the moon). The treaty also bans the establishment of military bases, installations, and fortifications, as well as the conduct of military manoeuvres, on celestial bodies.

But despite the evident intent of the treaty to designate space as a place of peaceful exploration, the narrow scope of Article IV on weapons of mass destruction arguably leaves gaps in the legal regime governing military activity in space. It fails to address, for example, the use of conventional weaponry in space and whether conventional weapons would be subject to the same restrictions enshrined in Article IV.

Fortunately, ambiguities in the application of international space law to military use have not gone unnoticed. In 2016, delegates to the United Nations Committee on the Peaceful Uses of Outer Space noted that more binding international legal instruments were necessary to prevent the placement of weapons in outer space and ensure the use of outer space for peaceful purposes. Also, international legal experts are working on a Manual on International Law Applicable to Military Uses of Outer Space, which will serve as a guidebook to fill the legal gaps regarding how, and to what extent, states can conduct military activities in outer space.

The day when human conflict transcends Earth’s boundaries may seem many years away. But technology in many areas, including those applicable to a military setting, are already used in space. It is therefore imperative to understand not only how international law applies to conflict over space rights more generally, but also to modern weapons technologies and their functions in space. The sooner we understand this, the better.

Erika Schneidereit is Counsel with the Department of Justice. The author's views are her and do not represent the views or the positions of the Department of Justice or those of the Government of Canada. The author's views are her own.