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Space law revisited (3/3): The regime of international liability in space

Analysis / Law and Conflict / New Technologies 10 mins read

Space law revisited (3/3): The regime of international liability in space

Earth viewed from the Suomi NPP satellite, January 2012. (NASA/Norman Kuring)

Outer space is becoming an arena for technological shows of force – whether by deployment of spy satellites or testing of weapons. What does international space law have to say on the militarization of space? In this three-post series, Pavle Kilibarda attempts a broader interpretation of the norms, one that would lead to a more pacifist reading of the law. The triad supplements Intercross’ series Why Outer Space Matters, which came out of the October 2016 Inaugural Plenary of the MILAMOS Project in Montreal, Canada.

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Having previously explored the general notion of “peaceful uses” of outer space, as well as the more specific regime governing the use of weapons of mass destruction, there is a third aspect of space law that is relevant to the ‘militarization’ or ‘weaponization’ of outer space: the system of international liability established by the Outer Space Treaty (OST) and the 1972 Liability Convention.

If it is accepted that space law provides no general prohibition of the militarization of outer space, examining the liability regime becomes particularly relevant. Whereas militarization in the broadest sense is legal, the concept of liability at least constrain the ‘weaponization of space’ (meant as the use of outer space for direct force deployment in situations of armed violence).

‘Liability’ here refers to a situation in which a State, having caused damage to the persons or property of another State, incurs an obligation to pay damages to that other State. This is already contemplated by Art. VII of the OST, which foresees that “each State Party to the Treaty (…) is internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by [its space object],” whether such damage is cased in outer space, on celestial bodies or the Earth itself. However, this guiding principle is only explored at length in the Liability Convention itself.

This latter treaty establishes a dual regime of liability, depending on whether the damage was caused on the surface of the Earth (as well as aircraft in flight) or in outer space. With respect to the former, “a launching State shall be absolutely liable to pay compensation for damage caused by its space object” (Art. II) — the sole exception to this mode of ‘absolute liability’ exists in situations when the damage may be shown to have been actually provoked by the other State Party. On the other hand, when it comes to damage caused to another space object, the launching State is liable only insofar as the damage may be shown to have been its ‘fault’ (Art. VI (1)).


The Liability Convention and armed conflict situations

Where does the militarization of outer space fit into all this? Taken at face value, the Liability Convention could be seen as a typical “peacetime” agreement, designed to govern regular, peaceful relations between States. In fact, the Liability Convention can be read as applying in situations of armed conflict, and therefore to the military use of space.

Its Preamble considers that “notwithstanding the precautionary measures to be taken by States and international intergovernmental organizations involved in the launching of space objects, damage may on occasion be caused by such objects.” This wording suggests that the Convention was designed primarily to accommodate for accidents, but by no means can it be construed as, a fortiori, not being applicable to damage caused deliberately.

For example, where Art. VI spells out the sole exceptions to absolute liability, it goes on to state explicitly that “no exoneration whatever shall be granted in cases where the damage has resulted from activities conducted by a launching State which are not in conformity with international law including, in particular, the Charter of the United Nations” or the OST. While the meaning of this provision may be debated, there is little doubt that what the drafters had in mind is the UN Charter’s prohibition on the threat and use of force in international relations. The very broad notion of ‘damage’ is defined as “loss of life, personal injury or other impairment of health; or loss of or damage to property of States or of persons, natural or juridical, or property of international intergovernmental organizations” (Art. I (a)). As a matter of treaty interpretation, it seems absurd to suggest that a treaty which clearly covers cases of accident would not also apply to damage caused deliberately, or is limited to deliberate damage caused outside of an armed conflict.

At the end of the day, the most contentious issue regarding the Liability Convention might not be when it applies, but rather to what objects. While space law uses the term ‘space object’ with some frequency, it never actually defines it, and all the Liability Convention has to say on the matter is that the phrase shall include “component parts of a space object as well as its launch vehicle and parts thereof” (Art. I (d)). This might imply that the drafters purposefully avoided giving an exact definition, as there is a certain limiting quality to defining legal terms, no matter how relevant.

That being said, the notion should be taken to be as inclusive as possible and include any man-made object launched into space, although a teleological analysis is likewise warranted in the sense that it is nevertheless somehow meant to function in space. Thus, a satellite or the Space Shuttle would certainly be considered space objects in the sense of the Liability Convention and the OST, whereas a missile, launched from one point on the surface of the Earth to another and briefly traversing the Kármán line, would not.


Space weapons, damage and compensation: an ‘indirect’ prohibition?

Bearing in mind the inherent difficulties in reading space law as prohibiting the broad notion of militarization or, even more narrowly, weaponization of space, the above reading of the Liability Convention suggests an unorthodox, yet potentially useful interpretation of the treaties.

For one, if any use of space weapons other than those mentioned specifically in treaty law (e.g. placing weapons of mass destruction in space or using celestial bodies for “non-peaceful” purposes) were to be in line with the OST, international liability may nevertheless be incurred for any damage caused to other States Parties by such use.

In a nutshell, it may not be illegal to use a space weapon (as a matter of space law) against another State, but whatever damage may be caused must be compensated. In times of armed conflict, international humanitarian law (IHL) covers the idea of reparations, yet these are never to be provided for otherwise legal acts of warfare. A contrario, the space liability regime would therefore amount to an “indirect” prohibition in practical terms: if compensation is to be paid for any damage done, can such damage be termed “legal” in the usual sense of the word?

Put otherwise: suppose that in a heated argument over a pint of beer in a bar, you suddenly smash your glass on the floor for dramatic effect. If the owner of the establishment was to come and ask you to refund the glass, would you say that you were allowed to break the glass in the first place? The very purpose of the compensation would be to indicate the illicit character of this kind of gesture.

On the other hand, while the Liability Convention boasts some ninety States Parties, there is simply too little practice regarding its application to grant credibility to any particular interpretation. The single claim under the Convention so far — made by Canada against the USSR after the 1978 Kosmos 954 incident — was made with respect to peacetime damages. It remains to be seen how such a claim would fare for damages made in armed conflict.

Similarly, even if the applicability of the Convention in armed conflict situations were to be confirmed, the inter-State nature of the liability regime would seemingly limit its relevance for non-international armed conflict, still usually fought within the territory of a single State. However, unlike IHL, which, as a rule, establishes obligations between belligerent parties, the Liability Convention foresees liability for any damage caused to the persons or property of another State. This would certainly be a limiting factor for the use of force from space even in times of non-international armed conflict, which are increasingly extraterritorial and often involve nationals of other countries.

This broad and inclusive interpretation of the Liability Convention, apart from being consistent with the pacifism inherent in modern international law, may likewise serve to put to rest the concerns of those who point to the more positive side of space militarization (such as the use of satellites for more precise guidance of weapons, resulting in less civilian “collateral damage”). Indeed, instead of limiting general military uses of space, the liability regime would restrain its weaponization. I believe that preventing the latter remains an issue the majority of humanists would aspire to.


This trilogy of blog posts has dealt with key legal aspects governing the issue of space militarization.

The peculiar circumstances which gave birth to the entire branch of international space law imply that the international community saw a chance for a new beginning in the ascendance of mankind to the stars. It was this perception that brought about the prohibition of claims of sovereignty on celestial objects, or the obligation to help astronauts regardless of their national origin. The same is true when it comes to mandating the “peaceful uses of outer space”. Militarization should be seen as antithetical to the inspired goals and ideals set by space law treaties.

While many scholars would conclude that ‘the final frontier’ is increasingly militarized, the law clearly places a number of limits on the military activities of States in outer space. The ‘pacifist’ approach to the law is therefore more than just idealism.

But simply interpreting the law is not enough. International law provides a framework for any scientific, commercial or even military activities in space. As such, it can restrict specific activities, but it may not direct them. The latter remains primarily the domain of policy.

If the exploration of space is truly to provide humanity with a chance to start over, it needs to be guided by the principles of true equality, solidarity and cooperation between all States — and they exclude all forms of militarism.

Pavle Kilibarda holds a LL.M. from the Geneva Academy of International Humanitarian Law and Human Rights. He previously worked at the ICRC’s legal training sector, the UNHCR office in Belgrade and the Belgrade Centre for Human Rights, engaging principally with the legal position of refugees and asylum-seekers in Serbia. He is the author of several publications dealing with international law and has spoken in various media outlets.

Also in this series…

  • Space law revisited (1/3): The notion of ‘peaceful uses’ and the Outer Space Treaty – Pavle Kilibarda, 7 November 2016.
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