Why Outer Space Matters: Dr. Dale Stephens Gives a Brief Introduction to International Humanitarian Law

Credit: NASA

Credit: NASA

Dr. Dale Stephens obtained his Doctorate (SJD) from Harvard Law School and is currently an Associate Professor at Adelaide Law School.  Prior to his academic appointment he served as a Legal Officer in the Royal Australian Navy, attaining the rank of Captain and occupying numerous staff officer and operational appointments throughout his 20 plus year naval career. In 2016 he was appointed as Editor In Chief of the Manual on International Law Applicable to Military Uses of Outer Space (MILAMOS), an international project led by Adelaide University Law School and McGill University (Canada) involving over 40 internationally respected practitioners and academics in the field. In this final post of the Why Outer Space Matters series, he gives a brief introduction on International Humanitarian Law. 

The views expressed in this article are solely those of the author and are not intended to represent any other party.

The idea of warfare in space may seem like a remote possibility, one better imagined occurring on the movie or television screen than in actual reality.  However, the fact is that since at least the 1990’s, the idea of warfare conducted from, to, or through space is not only gaining acceptance, but is considered inevitable by a growing number of observers.  Indeed, space based warfare is featuring in both emerging military war fighting doctrine as well as in a number of national Law of Armed Conflict Manuals, even if in the latter case it is outlined in very general terms.

Given this growing realization, it is timely to ask what law applies to regulate the conduct of armed conflict in space.  The answer to that question is a slightly vexed one.  Despite the volume and density of International Humanitarian Law (IHL) in numerous Treaties as well as (re) statements of customary international law, there is a precious little that is said about the application of IHL specifically to space.  One notable exception to this paucity is the 1977 ENMOD Convention that does expressly prohibit environmental techniques for changing the ‘dynamics, composition or structure of the Earth … or of outer space’.  Beyond this single reference, one would look in vain through the vast body of IHL to find ‘outer space’ mentioned specifically.  This then raises the foundational question of whether the general corpus of IHL can apply to outer space, given its lack of mention in the 1949 Geneva Conventions, the Additional Protocols or other key instruments of IHL.  

Does IHL Apply to Armed Conflict in Outer Space?

The intuitive answer to that question must be that IHL does apply to armed conflict in outer space.  Common Article 1 of the 1949 Geneva Conventions provide that ‘The High Contracting Parties undertake to respect and to ensure respect for the present Convention in all circumstances’ (emphasis mine), which surely means the law applies wherever and whenever armed conflict occurs.  Moreover, the International Court of Justice determined in the Nuclear Weapons Advisory Opinion that IHL ‘applies to all forms of warfare and to all kinds of weapons, those of the past, those of the present and those of the future’.   The sentiments expressed in that decision have also been reflected in ICJ cases such as the Corfu Channel case and Nicaragua case where the principles underlining IHL have been applied on the basis of ‘elementary considerations of humanity’, even where there was no de jure armed conflict.   Hence, given the breadth of expression in Article 1 of the Geneva Conventions coupled with the clear and consistent pattern of application of IHL (or the underlying principles) by the ICJ, it seems an unassailable conclusion that IHL would apply to regulate armed conflict occurring from, to, or through outer space.

Accepting therefore that IHL would apply to armed conflict in outer space, how would it be manifested? Military reliance on satellites is increasing exponentially and is realized in numerous national activities including Intelligence, Surveillance and Reconnaissance, communications, space situational awareness and early warning ballistic defense.  While there are dedicated military satellites, civilian commercial satellites are also used (through contractual means) for military purposes.  Given such usefulness and increasing military dependency on space based assets, it is not surprising that there is also being developed a cascading array of specialized weapon systems that can target (enemy) satellites.  Such weapons include kinetic anti satellite missiles (ASATs), co-orbital ASATs, directed energy weapons, cyber weapons and electro magnetic pulse weapons.  The only weapons system that is prohibited in space are weapons of mass destruction (i.e nuclear weapons) in full orbit. Such prohibition comes not from IHL, but rather is contained in Article IV of the Outer Space Treaty. The US Law of War Manual acknowledges this prohibition and observes, alternatively, that all other weapon systems may lawfully be deployed and, prima facie, used in space.

Assuming armed conflict involving space based assets, the central principles of distinction, proportionality and precaution that underpin IHL would necessarily apply to regulate armed conflict in space. Such principles would also provide necessary protections for civilians and civilian uses of space-based assets to the limits of their application.  While such application is well understood in the terrestrial environment, they take on a different complexion in space. 


The principle of distinction would apply in respect of targeting people and objects in space.  Hence, it would necessarily apply to military astronauts engaged in armed conflict in outer space, just as much as it would apply on land, sea or air.  One intriguing legal conundrum that arises in this context is the application of the 1968 Astronaut Rescue and Return Agreement, which mandates the return of a foreign astronaut that makes a forced landing outside of their national territory.  In the context of a downed enemy military astronaut within the territory of a belligerent country, such astronaut would ordinarily have prisoner of war status under the Third Geneva Convention.  However under the 1968 Agreement, he/she is to be returned ‘promptly’ to their home country.  No doubt, resolution of this issue would rely on concepts of lex specialis between the two treaty regimes, but which treaty regime would have priority? Perhaps a compromise might be reached where the military astronaut is returned as PW ‘on parole’. 

In respect of targeting military objectives (i.e. property) it is well settled that the principle of distinction does not prohibit attacking ‘dual use’ objects.  In the space context this would include civilian satellites that are used to acquire and pass on militarily significant information relating to reconnaissance, electronic intelligence, early warning systems, ocean surveillance systems (that can detect surface and subsurface movement), radar calibration and communications.  This would also include satellites that provide space based navigational assistance to weapons systems (such as the US GPS). Of course GPS (and the Russian (GLONASS), European (Galileo), Chinese (BeiDou) and Indian (IRNSS) equivalents) also serves fundamental civilian uses, including for example communications, banking, internet, medicine, agriculture, transport and a myriad of other uses that would need to factor in a proportionality assessment. However, prima facie these dual use functions do not automatically render such a satellite protected, if it also serves a military function.     


As is well established in IHL, the test of proportionality requires assessment of the possible civilian consequences of an attack upon a lawful target and requires that attacks are prohibited in the following circumstances:

‘An attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated’ 

There is no set mathematical rule of what is an acceptable civilian loss, though Courts have required than an objective ‘reasonableness’ test be applied. In the space context the issue is less about direct civilian loss, but rather causally connected indirect civilian loss.  At present, Unmanned Aerial Vehicles (UAV’s) require access to satellite navigational services.  Indeed, many of the world’s precision munitions are similarly reliant on global navigation satellite systems.  Thus the question would need to be asked as to the military advantage of undermining the enemy’s capacity to use such UAV’s/munitions and whether such destruction would be so great that the loss of something like the US GPS or Russian GLONASS system would be ‘excessive’ to the military advantage anticipated? If not excessive, then they may be lawfully attacked.  The resulting civilian loss of global navigation satellite systems would obviously be enormous, however the legal test is not ‘extensive’ loss overall, but rather ‘excessive’ loss to the anticipated military advantage.


Finally, is the application of the principle of precaution that requires that an attacking force take all ‘feasible’ precautions in the choice of means and methods of attack with a view to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects.  The question of precautions in attack has particular relevance in the field of space-based warfare.  While physical means of attacking satellites have been proven, the resulting debris created from using a missile or otherwise creating actual physical damage to a satellite, poses a significant problem to safety and continued civilian space use.  The laws of physics apply in the context of kinetic attack such that destruction of a satellite and resulting debris doesn't merely fall to the ground, as is the case of terrestrial warfare, but rather circles the earth at hyper velocity (up to 24,000 kilometres per hour). 

Accordingly, military planners would be required to map the projected trajectories of the debris and planned orbits, and possible resulting collisions (the ‘Kessler effect’ referred to in an earlier Intercross post by Brian Weeden), must be taken into account in the military legal planning process.  Given these facts, the principle of precaution might mandate that, as a matter of law, kinetic means are not to be used when attacking an enemy military satellite. Rather, there may be a requirement to use cyber means or perhaps a highly specific directed energy weapon to disrupt the function of a satellite without destroying it.


The MILAMOS (Manual on International Law Applicable to Military Uses of Outer Space) project is a three-year international effort to identify and articulate the law that applies to military uses of outer space.  A key component of this project is the specific focus on armed conflict in space.  Clearly, in the event of an armed conflict involving space based assets, all civilian protections and priorities as provided for in IHL must apply. This project will ensure that these IHL rules are faithfully recorded and, more challengingly, are given a contextual application.  The Project is being led by the University of Adelaide (Australia) and McGill University (Canada) and brings together legal and technical specialists from Governments, the ICRC, Non Government Organizations and academia to discuss and agree on those rules that apply and how they apply.  Importantly, the participation of all experts in this project is strictly in a personal capacity and this is designed to optimise the production of an objective, impartial and neutral account of the applicable legal framework. The resulting Manual will take its place alongside other recent manuals that the ICRC has participated in dealing with identifying rules of IHL applicable to naval, air and cyber war contexts.  We do live in the ‘age of the manual’ and it is therefore critical that this project be successful so as to enhance the continued sustainability of humankind’s ventures in outer space.      

Schedule of blog posts:

This blog series comes out of the October 2016 Inaugural Plenary of the MILAMOS Project in Montreal, Canada sponsored by the McGill Centre for Research in Air and Space Law (CRASL), the University of Adelaide's Research Unit on Military Law and Ethics (RUMLAE). The ICRC participated in the plenary as an Institutional Contributer.


Dr. Dale Stephens

Dr Dale Stephens obtained his Doctorate (SJD) from Harvard Law School and is currently an Associate Professor at Adelaide Law School.  Prior to his academic appointment he served as a Legal Officer in the Royal Australian Navy, attaining the rank of Captain and occupying numerous staff officer and operational appointments throughout his 20 plus year naval career.

His operational deployments include East Timor in 1999 and 2000, and Iraq in 2005 and 2008.  Dr Stephens is currently Director of the Adelaide Research Unit on Military Law and Ethics (RUMLAE). He is also an active board member of the Australian Yearbook of International Law and Chair of the South Australian Red Cross International Humanitarian Law Committee.  In 2016 he was appointed as Editor In Chief of the Manual on International Law Applicable to Military Uses of Outer Space (MILAMOS), an international project led by Adelaide University Law School and McGill University (Canada) involving over 40 internationally respected practitioners and academics in the field.