Journal of Law, Information and Science
Regulating the Use of Unmanned Combat Vehicles: Are General Principles of International Humanitarian Law Sufficient?
COMMENT BY MEREDITH HAGGER AND TIM MCCORMACK[*]
Some weapons are prohibited by a specific multilateral treaty regime and others by customary law. Neither source of prohibition applies to unmanned combat vehicles (UCVs). In the absence of a specific legal prohibition, UCVs can lawfully be deployed in armed conflict provided their use is consistent with so-called general principles of international humanitarian law (IHL). These general principles limit or restrict the circumstances in which UCVs can lawfully be deployed. In combat operations militaries utilising UCV technology are closely scrutinised and generally do try to ensure compliance with IHL. The real concerns lie with dubious usage of UCVs in covert operations where the IHL framework seems to provide a conveniently permissive legal regime, there is an apparent absence of any effective review of compliance with IHL and no accountability for alleged violations of the law. In some circumstances it is highly questionable whether IHL is the applicable legal framework.
The use of unmanned combat vehicles (UCVs) in armed conflict is not a particularly new phenomenon. Nevertheless, the forms that such weapons now take, as well as the prevalence of their use, have increased exponentially in the past few years. This dramatic increase has, in turn, been accompanied by a variety of opinions as to the legality and the desirability of battlefield use of UCVs. The intention of this paper is to identify and assess the sufficiency of the legal framework applicable to UCVs in armed conflict. The so-called ‘general principles of International Humanitarian Law’ exist to ensure that categories of weapons not otherwise prohibited by conventional or customary international law, are nevertheless subject to laws that aim to alleviate human suffering in armed conflict. Incongruence sometimes exists between theory and practice. We will discuss some of the limitations to the efficacy of these ‘general principles’ to effectively regulate the use of convenient weapons with high degrees of military utility.
In the Nuclear Weapons Advisory Opinion, the International Court of Justice (ICJ) considered whether there was a general prohibition on the use of nuclear weapons under international law. Although the Opinion has been criticised by many, it provides one of the most detailed judicial considerations of the circumstances in which a category of weapons will be illegal per se under international law. In circumstances where a particular category of weapon is not illegal per se, the Opinion affirms the applicability of the general principles of international humanitarian law (IHL) to the use of such weapons — including nuclear weapons — in armed conflict. The Opinion then, constitutes a useful starting point for identifying the law applicable to UCAVs in armed conflict.
This paper commences with a brief overview of the ICJ’s decision in the Nuclear Weapons Advisory Opinion, and then applies the relevant legal principles identified in that case to UCV technology in current use. Given that there is currently no treaty or customary prohibition on UCAV technology, the use of these weapons in armed conflict is regulated by general principles of IHL. In order to explore whether this legal framework is sufficient, this paper will consider the circumstances that led to an international prohibition on the use of cluster munitions and land mines. These two examples demonstrate the way the international community may react when general principles of IHL are deemed insufficient to regulate the effects of a particular weapon. It also enables a comparison between the current level of opposition to UCAVs, and campaigns that lead to the international prohibition of weapons in the past. The final part of the paper analyses criticism of the increasing incidence of UCAV attacks, and concludes that the principal focus of concern is not generally on military utilisation of the technology in the theatre of combat operations. Rather, of much greater concern are covert targeted killing programs which currently appear to operate beyond the law with a complete absence of transparency and accountability.
In 1994, the General Assembly of the United Nations requested an Advisory Opinion of the International Court of Justice on whether the threat or use of nuclear weapons is permitted in any circumstances under international law. The resulting Opinion of the Court implicitly recognised that there are broadly two categories of weapons. The first category consists of those weapons that are illegal per se in international law. The use of such weapons is never permitted, irrespective of the circumstances in which they are used. The second category consists of those weapons that are not illegal per se and so, consequently, may be used in armed conflict, subject to legal regulation. The basis of the Court’s discussion was the premise that, ‘the illegality of the use of certain weapons as such does not result from an absence of authorization but, on the contrary, is formulated in terms of prohibition.’
The Court thus began by considering whether there was a specific prohibition in international law on the use of nuclear weapons. Clearly, such a prohibition could be derived from a multilateral treaty, or from customary law. In relation to the former source, the Court found that there was no multilateral treaty specifically prohibiting the threat or use of nuclear weapons in all circumstances. The Court acknowledged that various agreements dealing with nuclear weapons ‘certainly point to an increasing concern in the international community with these weapons.’ However, the Court found that these treaties, by themselves, do not constitute a prohibition on the threat or use of nuclear weapons.
The leading multilateral treaty dealing with nuclear weapons is the 1968 Nuclear Non-Proliferation Treaty (‘NPT’). Unlike the 1972 Biological Weapons Convention or the 1993 Chemical Weapons Convention, the NPT does not constitute a comprehensive ban on all nuclear weapons. Nevertheless, for 184 of the 189 current States Parties, the NPT does constitute a comprehensive ban on nuclear weapons. Each of those 184 states has either ratified or acceded to the treaty as a ‘non-nuclear weapon State Party’ and, as such, is obliged not to ‘receive, manufacture or acquire’ nuclear weapons, not to possess them and not to ‘transfer’ them to any other state, nor to assist any other state to ‘manufacture or acquire’ nuclear weapons. Iran is a non-nuclear weapons State Party to the NPT and has been accused of violating its treaty obligations in the development of its nuclear program. North Korea, prior to its withdrawal from the NPT in 2003, was similarly accused of violating its obligations as a non-nuclear weapons state under the NPT. Since its withdrawal, North Korea has been the subject of Security Council resolutions deploring both its withdrawal from the NPT and its nuclear weapons program, including the nuclear test conducted in 2009, and demanding that North Korea immediately retract its announcement of withdrawal. Israel, India and Pakistan, in contrast, have never participated in the NPT and so are not bound by the treaty’s prohibitions.
Despite the fact that the overwhelming majority of States Parties to the NPT have subjected themselves to a comprehensive treaty ban on nuclear weapons, five States Parties are exempt from the prohibition and are entitled to retain their nuclear weapons stockpiles as ‘nuclear weapon State Parties’. Those five states had all ‘manufactured and exploded a nuclear weapon or other nuclear explosive device prior to 1 January 1967’ and, coincidentally, happen to be the five permanent members of the UN Security Council. Because five states are permitted to retain nuclear weapons under the terms of the NPT, the ICJ could not declare the threat or use of nuclear weapons illegal in all circumstances by virtue of a multilateral treaty prohibition.
As for the existence of a customary prohibition on the threat or use of nuclear weapons, the Court acknowledged the argument advanced by some states that there had been a considerable period of time during which states in possession of nuclear weapons had refrained from using them. However, the Court concluded that ‘members of the international community are profoundly divided on the matter of whether non-recourse to nuclear weapons over the past 50 years constitutes expression of opinio juris [as to the existence of a prohibition on use].’ The divided opinion as to the legal effect of non-use of nuclear weapons undermined any evidence of the requisite opinio juris to support the existence of a customary prohibition.
Having found no specific prohibition on the use of nuclear weapons under conventional or customary international law, the Court considered whether there were other areas of international law from which a prohibition on the use of nuclear weapons may be derived. In this regard, the Court considered human rights law, the law pertaining to genocide and to environmental protection, and international humanitarian law. The Court found that human rights law and the law dealing with genocide and environmental protection may be used to determine that a particular the use of a weapon is illegal in certain circumstances. However, a general prohibition on the use of nuclear weapons, and thus arguably any other weapon, could not be derived from these areas of law. Although the Court recognised that general principles of IHL could theoretically render the use of a weapon illegal in all circumstances, it found that there is no general prohibition of nuclear weapons in IHL. Of course, any use of nuclear weapons in armed conflict must conform to the general principles of this body of law — principles which apply to the use of every category of weapon in armed conflict irrespective of whether there is a specific prohibition on the use of that weapon. This aspect of the Court’s decision will be considered in more detail below. Suffice to say here that the Court considered that the use of nuclear weapons ‘seems scarcely reconcilable’ with the general principles of IHL. Nevertheless, the Court was unable to ‘conclude with certainty’ that the use of nuclear weapons would be at variance with such principles ‘in any circumstance.’
IHL regulates the conduct of military hostilities in order to limit the effects of armed conflict, by restricting the method and means of war and protecting persons who are not or are no longer participating in hostilities. The principles of IHL are codified in various treaties, principally the Hague and Geneva Conventions. In addition, as the ICJ noted in the Nuclear Weapons case, many of these rules also ‘constitute intransgressible principles of international customary law.’
In relation to the application of IHL to specific weapons, Judge Higgins stated in the Nuclear Weapons Advisory Opinion that:
The role of humanitarian law (in contrast to treaties of specific weapon prohibition) is to prescribe legal requirements of conduct rather than to give “generalized” answers about particular weapons. I do not, however, exclude the possibility that such a weapon could be unlawful by reference to the humanitarian law, if its use could never comply with its requirements — no matter what specific type within that class of weapon was being used and no matter where it might be used.
While Judge Higgins dissented in the case, her position on the applicability of IHL seems to be consistent with that of the majority opinion. Further, the Court noted that general principles of IHL do not solely regulate ‘weaponry of an earlier time’. Instead, ‘the intrinsically humanitarian character of the legal principles in question ... permeates the entire law of armed conflict and 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 Court considered that, in the absence of a specific prohibition, the use of a particular weapon could still be illegal if that use always violated one of the general principles of IHL, considered below.
One of the general principles of IHL considered by the Court was the customary prohibition on the use of weapons which cause superfluous injury or unnecessary suffering to combatants. In his dissenting opinion, Judge Shahabuddeen explained the operation of the prohibition as follows: ‘the use of a weapon which caused the kind of suffering that poison gas caused was simply repugnant to the public conscience, and so unacceptable to States whatever might be the military advantage sought to be achieved.’ He further gave the example of dum-dum bullets, which were ‘deliberately crafted so as to cause unnecessary suffering’, and which fell foul of this prohibition. The prohibition is codified in Article 35(2) of the 1977 Additional Protocol I to the Geneva Conventions, and also in Article 23 of the 1907 Hague Regulations Respecting the Laws and Customs of War on Land. It is also universally recognised as a customary norm in both international and non-international armed conflicts. The Rome Statute, for example, includes the war crime of ‘employing weapons, projectiles and material and methods of warfare which are of a nature to cause superfluous injury or unnecessary suffering’ in the subject matter jurisdiction of the International Criminal Court.
Many assume that the prohibition is devoid of practical meaning in the absence of a multilateral agreement amongst states prohibiting a category of weapons. No category of weapon has been explicitly prohibited by the international community on the basis of the customary rule reflected in Article 35(2) of Additional Protocol I. However, anecdotal evidence suggests that some states have unilaterally prohibited the development of certain weapons systems on the basis of legal opinion that such weapons would offend the customary prohibition. Details of proposed new weapons systems are usually classified and not in the public domain either for commercial-in-confidence or national security (or both) reasons and so it is impossible to substantiate the application of the customary prohibition to prevent the development of new weapons systems. In any case, for present purposes that impossibility is immaterial. The potential for low-yield tactical nuclear weapons to be used consistently with general principles of IHL is sufficient to find that nuclear weapons are not ipso facto of a nature to cause superfluous injury or unnecessary suffering. Indeed, the Court was unable to find that nuclear weapons automatically fell foul of this customary prohibition, although it stopped short of identifying specific scenarios in which nuclear weapons may be used in ways which do not cause superfluous injury or unnecessary suffering.
The Court also referred to the so-called Martens Clause as an ‘effective means of addressing the rapid evolution of military technology.’ The Martens Clause was originally included in the 1899 Hague Convention II with Respect to the Laws and Customs of War on Land, and a revised version was subsequently included in the 1977 Additional Protocol I as follows: ‘In cases not covered by this Protocol or by other international agreements, civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience.’
The Court noted that the Martens Clause, as expressed in Additional Protocol I, was an ‘expression of pre-existing customary law’. The legal effects of the Martens Clause have been subject to a number of different interpretations, as demonstrated by the variety of opinions expressed in the oral and written submissions of various states in the Nuclear Weapons case. At its widest, the Martens Clause has been interpreted to mean that conduct during an armed conflict will be subject to customary rules and to the requirements of humanity and public conscience, in the absence of a treaty provision covering that particular conduct. The Court did not specifically consider how the Martens Clause would apply to nuclear weapons, and thus provided little guidance on the scope of the Clause. In the International Criminal Tribunal for the former Yugoslavia (ICTY) case of Prosecutor v Kupreskic, the Trial Chamber noted that:
This Clause may not be taken to mean that the “principles of humanity” and the “dictates of public conscience” have been elevated to the rank of independent sources of international law, for this conclusion is belied by international practice. However, this clause enjoins, as a minimum, reference to those principles and dictates any time a rule of international humanitarian law is not sufficiently rigorous or precise: in those instances the scope and purport of the rule must be defined with reference to those principles and dictates.
Meron argues that the decision of the ICJ in the Nuclear Weapons case indicates that while the Martens clause ‘should be taken into consideration in evaluating the legality of weapons and methods of war ... except in extreme cases, its references to principles of humanity and dictates of public conscience cannot, alone, delegitimize weapons and methods of war, especially in contested cases.’
One of the most fundamental principles of IHL — integral to the raison d’être of this body of law and characterised in Additional Protocol I as a ‘basic rule’ — is the distinction between civilians and combatants. Civilians and civilian objects must never be the object of an attack and indiscriminate attacks are prohibited. Indiscriminate attacks include those in which the chosen weapons are incapable of distinguishing between military and civilian objects. The ICJ referred to this rule as a ‘cardinal’ principle of IHL.
A number of states in the Nuclear Weapons case argued that nuclear weapons are unable to distinguish between civilians and combatants, and that their effects are largely uncontrollable, and cannot be restricted. They thus argued that recourse to nuclear weapons could never be compatible with the principles and rules of humanitarian law and must therefore be considered prohibited. This is a readily comprehensible position. Any use of a nuclear weapon against a military objective in close physical proximity to civilians and civilian property will surely constitute an indiscriminate attack. Even if the blast effects of the detonation of a low-yield nuclear weapon could be confined to the military objective, the release of radioactivity could not be. The devastating effects of radioactive fallout from accidents at nuclear power plants in Chernobyl and Fukushima are testament enough to this reality — even without contemplating the effects of the actual use of nuclear weapons against the cities of Hiroshima and Nagasaki. It is presumably this reality that led the majority of the ICJ to opine that any use of nuclear weapons would be ‘scarcely reconcilable’ with the general principles of IHL.
The characterisation ‘scarcely reconcilable’, however, suggests the possibility, however remote, that some use may be reconcilable with the general principles of IHL. The Court did not identify any such possibility although two scenarios are regularly cited. Both involve low-yield tactical nuclear weapons deployed against targets far removed from the civilian population. The first scenario involves an attack on a naval vessel on the high seas and the second involves an attack on an underground military facility in a physical location remote from civilian residential areas (a desert or other uninhabited location). In both scenarios there may still be issues of radioactive contamination, but the theoretical possibility of conformity to general principles of IHL remains. Intriguingly, the Court did not rely on the possibility of conformity with general principles to reach its majority view that it could not declare the threat or use of nuclear weapons illegal in all circumstances. Instead, after declaring any use ‘scarcely reconcilable’ with general principles, the Court leaps to the jus ad bellum — to cases of self-defence in extremis where the very survival of the state is at stake — to justify its non-finding. That aspect of the decision has been criticised elsewhere.
Given the Court’s finding that even nuclear weapons are not inherently incapable of distinguishing between combatants and civilians, it is extremely unlikely that any other category of weapon will cross this threshold of illegality. Thus it may be said that the rule on distinction acts to regulate the use of weapons, rather than constituting a blanket prohibition. It follows that any indiscriminate use of a weapon in armed conflict is a war crime and it is the particular circumstances of the attack, rather than the particular specifics of the weapon of choice, which constitutes the serious violation of IHL.
There is no specific international law prohibition — conventional or customary — on the use of unmanned combat vehicles (UCVs). Whilst there are a few international treaties that deal with unmanned vehicles, none of these provide anything that remotely resembles a prohibition on their use. The most prominent of these agreements are the non-binding Missile Control Technology Regime (MTCR) and the Wassenaar Arrangement, both of which constitute export control agreements. The MTCR seeks to coordinate national export licensing in order to, inter alia, prevent the proliferation of unmanned delivery systems capable of delivering weapons of mass destruction. The Wassenaar Arrangement similarly seeks to prevent destabilising accumulations of, inter alia, unmanned vehicle (UV) technology, by promoting ‘transparency and greater responsibility in transfers of conventional arms and dual-use goods and technologies.’ Some commentators have suggested that unmanned aerial vehicles may also be covered by the 1987 Intermediate-Range Nuclear Forces Treaty, due to their similarity to cruise missiles, or the 1992 Treaty on Conventional Armed Forces in Europe as they fall within the definition of ‘combat aircraft.’ While both of these treaties seek to limit the overall number of particular weapons possessed by member states, neither impose particularly onerous limits, even assuming unmanned aerial vehicles are covered. In addition, both treaties have only limited participation (US, European states and Russia).
The absence of a specific treaty prohibition is congruent with the lack of any evidence that UCVs are prohibited by customary norm. The widespread use of UCVs in armed conflict (there are currently hundreds of UCVs in use in Iraq, Afghanistan, Pakistan and the Occupied Palestinian Territories, for example, and more than 40 countries are reportedly developing or purchasing military robots) suggests that states do not believe that UCVs are prohibited by customary international law.
Unmanned combat aerial vehicles (UCAVs) are capable of carrying a variety of different munitions, including Hellfire missiles; guided bomb units (GBU) such as the Paveway 12; and lighter missiles, including the 33kg fibre-optic guided Rafael Spike-ER. In addition, commentators have noted that UCAVs could be used as platforms for launching nuclear weapons, as well as chemical and biological weapons. It is thus necessary to distinguish between the weapons carried by the UCAV, and the unmanned platform itself. As Boothby notes, ‘the weapon that is being carried on and used by, or guided by, the UCV will need to be the subject of a separate legal review.’ Thus as long as overall operational control and the decision to use lethal force remain with a human controller, UCAVs do not appear to raise any issues separate from those raised by the weapons systems attached.
Evidently, there is no basis for arguing that UCAV technology that is currently in use is inherently of a ‘nature to cause superfluous injury or unnecessary suffering’ or that the ‘dictates of public conscience’ militate against the use of UCAVs. In addition, the weapons deployed on UCAVs that have been used in armed conflict to date have generally been considered ‘precision’ weapons, capable of a high degree of accuracy and the ability to home in on the intended target — the quintessential embodiment of the rule of distinction. In 2009, Human Rights Watch, for example, issued a report into the use of drone-launched missiles by Israel in the Gaza strip. This report noted that Israeli drones are equipped with high-resolution cameras and advanced sensors, and that the ‘missile launched from a drone carries its own cameras that allow the operator to observe the target from the moment of firing to impact’ and divert the weapon ‘if doubts arise about a target after the missile has been launched.’ The report continued, ‘with these advanced visual capabilities, drone operators who exercised the proper degree of care should have been able to tell the difference between legitimate targets and civilians [emphasis added].’ Finally, the report considered that given ‘the weapon’s highly discriminate nature’ authorities should review every mission ‘involving drone-launched missiles in which civilians were wounded or killed.’
Similarly, the Goldstone Report, which investigated possible breaches of IHL in the Gaza conflict, stated that the UCAVs used by Israel on the 27 December 2008 attack against the Namar wells group ‘are capable of a high degree of precision.’ There can be no suggestion that the UCAVs currently in use in armed conflict are incapable of discriminating between civilians and combatants. Arguably, the more significant issue is the question of accountability for breaches of IHL when UCAVs are used (or the weapons they are carrying are deployed) in an indiscriminate attack. According to Michael Schmitt:
Since drones employ precision guided munitions such as laser-guided missiles or the JDAM, they are self-evidently not indiscriminate means of warfare. On the contrary, they are far more capable of being aimed at targets than many other weapons systems commonly employed on the battlefield. However, the indiscriminate use of a discriminate weapon is unlawful.
We will return to the issue of accountability for breaches of IHL in the use of UCAVs later.
In addition to distinguishing between combatants and civilians and avoiding indiscriminate attacks, military decision makers must also respect the rule on proportionality. Whenever an attack is directed at a military objective, any expected impact that attack will have on civilians or civilian objects must be proportionate to the expected military gain from the attack. The rule on proportionality, another cardinal principle of IHL, is codified in Additional Protocol I, and is also a well-established principle of customary international law. According to Boothby:
This proportionality rule has, however, no direct applicability to the legitimacy of a weapon. It is not a criterion against which the legitimacy of a weapon can sensibly be considered, because what is proportionate can only meaningfully be determined in relation to an attack on a particular occasion, perhaps at a specific time, using particular weapons and specified attack profiles. The case-specific nature of these factors means that the proportionality rule is not something of direct relevance to weapons law.
It is most likely for this reason that the Court in the Nuclear Weapons case did not consider the principle of proportionality in any detail in its analysis of whether nuclear weapons are illegal per se. The analysis here is similar to that for the rule on distinction and the prohibition on indiscriminate attacks. Any use of high-yield nuclear weapons against or in close physical proximity to a densely populated civilian residential area would surely constitute disproportionate military force. The expected widespread deaths of civilians from blast and heat, the expected longer-term consequences of exposure of survivors to radioactive contamination, the expected destruction of civilian property and radioactive contamination of civilian land, infrastructure and buildings would clearly be excessive in relation to any expected military advantage.
Although nuclear holocaust is a quintessentially disproportionate scenario, nuclear weapons could also theoretically be used entirely consistently with the rule on proportionality (as per the scenarios outlined above). The relevant test for proportionality is not applied to the technical specifications of the particular weapon, but to the manner in which it is used. That is as true for nuclear weapons as it is for UCAVs and for all the various weapons systems that can be deployed on a UCAV. Any disproportionate use of weapons deployed through the medium of a UCAV would constitute a war crime and those responsible for the disproportionate attack could be held criminally responsible for the violation of IHL.
In 2005, in a case commonly referred to as the ‘targeted killings’ case, the Israeli Supreme Court considered the legality of the policy of ‘preventative strikes’ carried out by Israel against Palestinian militants in the Occupied Palestinian Territories. Some of these have been carried out using drones. The plaintiffs in that case argued that the ‘targeted killings policy does not withstand the proportionality requirement,’ and ‘does not discriminate between terrorists and innocent persons.’ The Court considered that IHL applied to the killings, and concluded ‘we cannot determine that a preventative strike is always legal, just as we cannot determine that it is always illegal.’ Instead, the Court emphasised that proportionality must be judged on a ‘case by case’ basis. This decision indicates drones currently in use by Israel do not, in and of themselves, violate the principle of proportionality. Rather, the relevant consideration is the way they are used in particular circumstances.
The most remarkable characteristic of UV technology is its potential to be deployed in the place of a human decision maker. This aspect of the technology is what distinguishes it from traditional weapons, and perhaps what requires a consideration of the principle of proportionality when determining its legality. As various commentators have argued, UCVs will gradually become more autonomous and will one day be capable of operating autonomously ‘to locate their own targets and destroy them without human intervention.’ Estimates of when this will be possible generally range between 5 and 15 years, although some consider that it will take significantly longer. The UK Ministry of Defence has stated that it ‘currently has no intention to develop systems that operate without human intervention in the weapon command and control chain.’ Similarly, the United States Air Force has stated that the decision to authorise ‘a machine to make lethal combat decisions is contingent upon political and military leaders resolving legal and ethical questions.’ Nevertheless, if a weapon is designed to make targeting decisions without human oversight, it must be capable of accurately distinguishing between combatants and civilians, and also of determining when an attack will be proportionate. If it is never capable of doing so, then, using the Court’s reasoning in the Nuclear Weapons case, its use must be considered illegal.
Sharkey has argued that ‘there is no way for a robot to perform the human subjective balancing act required to make proportionality decisions.’ He points out that there is no clear, objective method for determining what is proportionate, and that it is difficult, if not impossible, to ‘calculate a value’ for the actual military advantage gained from any particular attack. He argues that UVs would face similar problems with the related principle of distinction, discussed above, due to the difficulties in determining who constitutes a civilian in modern armed conflict. On the other hand, Alston has pointed out that robots may be able to use lethal force more conservatively than humans, and reduce collateral damage and other mistakes made by humans: ‘they may also be able to avoid mistakes or harm resulting from human emotions or states, such as fear, tiredness, and the desire for revenge.’ Whether this is the case, remains to be seen. In any event, it is worth recalling that Additional Protocol I contains an obligation on state parties to determine whether the use of a new weapon would ‘in some or all circumstances, be prohibited by this Protocol or by any other rule of international law applicable.’
Whatever the future developments in relation to new UCV technologies, there are myriad sources of discomfort in the increasing contemporary utilisation — particularly of UCAVs — to launch lethal attacks. The theoretical possibility that the deployment of lethal force by an UCAV can be undertaken entirely consistently with general principles of IHL will not assuage concerns about the widespread use of UCAV technology. By this we do not mean to imply that compliance with IHL is only a remote theoretical possibility. It may well be the case that many, perhaps even a majority, of killings by pilotless drones are perpetrated lawfully. Rather, our suggestion here is that there is a widely held view that the legality of a substantial proportion of such killings is dubious. The fact that general principles of IHL apply to the use of UCAVs in armed conflict, and the possibilities of criminal accountability for violation of those principles are insufficient in and of themselves to assuage existing concerns.
The perceived limitations of general principles of IHL as the primary source of legal regulation of a category of weapons are not restricted to the utilisation of UCAV technology. Many states came to the view that general principles of IHL were inadequate to address the deleterious humanitarian consequences of the widespread use of both anti-personnel landmines and cluster munitions for example. There have certainly been instances of ‘responsible’ deployment of anti-personnel landmines and cluster munitions — discriminately, proportionately and with optimum care taken to minimise civilian casualties — that were entirely consistent with general principles of IHL. These examples demonstrate that it is possible to deploy both categories of weapon in strict compliance with IHL. However, for every example of ‘responsible’ use, there seem to be many more examples of widespread deployment of these weapons indiscriminately, disproportionately or otherwise carelessly with diabolical consequences for affected civilian populations.
In relation to cluster munitions, for example, in March 2006, the following conclusion was presented to the Group of Governmental Experts (GGE) to the Certain Conventional Weapons Convention discussions on Protocol V and the issue of explosive remnants of war (ERW) at the UN in Geneva:
It is our conclusion that Protocol V to the CCW and the existing rules of IHL are specific and comprehensive enough to deal adequately with the problem of ERW provided that those rules are effectively implemented. That proviso is an important one. It is not adequate for States that want to use cluster munitions, for example, simply to assert that their use of such weapons is consistent with general “principles” of IHL without a genuine commitment to implement the binding legal rules effectively. Increasingly demands are made for independent scrutiny of choices of weapon, selection of targets and the conduct of military operations.
Furthermore, there is a growing international expectation that those responsible for violations of the law will be held criminally accountable and will not be allowed to experience impunity for their crimes. There is much the GGE can do to encourage States Parties to the CCW to take their existing IHL obligations more seriously — including the implementation of effective measures for enforcement of violations. It is surely the case that if, following the adoption of Protocol V, the ERW problem only increases in severity and in its threat to civilian populations affected by armed conflict, many in the international community will argue for a more specific and substantive response — including, perhaps, a treaty ban on cluster munitions. The onus is on user States to demonstrate that such weapons can be used consistently with the binding obligations of IHL.
Within four months of the presentation of this conclusion in Geneva, violence erupted in Southern Lebanon and Northern Israel between Hezbollah and Israeli military forces. One feature of the conflict was the controversial and widespread use of cluster munitions by Israeli forces across swathes of arable land in Southern Lebanon. The unusually high rate of unexploded ordnance (some estimates up to 40% of sub-munitions) constituted a humanitarian crisis as the civilian population sought to return to towns and villages in the affected area post-conflict. Borrie claimed that this conflict ‘provided irrefutable evidence that cluster munitions are deeply problematic weapons in terms of their impact on civilians, even when used by a professionally trained army intimately familiar with International Humanitarian Law requirements.’ The adverse humanitarian consequences of this particular use of cluster munitions also provided a major impetus for successful multilateral negotiations for a comprehensive treaty prohibition on cluster munitions.
We are not suggesting here that contemporary use of UCAV technology for attacks is directly analogous to the humanitarian impact of the widespread deployment of cluster munitions in the latter half of 2006. Rather, the example of one major catalyst resulting in the negotiation of a multilateral treaty ban on clusters is illustrative of what can happen when the international community develops the view that general principles of IHL are not an adequate constraint on the use (or misuse) of a particular category of weapon. If the current use of UCAVs continues to escalate, those engaged in the use of the technology and its weapons system will likely experience increasing pressure for greater transparency, accountability and possibly specific legal regulation of the use of the technology.
Intriguingly, though, discomfort about the increasing reliance on UCAVs is generally not focused on the military utilisation of the technology in the theatre of operations. It is widely accepted that such use is regulated by IHL; that militaries utilising the technology usually attempt to ensure that each UCAV attack is consistent with IHL; and that many such attacks are scrutinised both internally (within military structures) and externally by NGOs, the media and other observers who raise concerns about the relevant rules of IHL when appropriate. It is also expected that whenever there are allegations of serious violations of IHL in relation to a UCAV-launched attack, the incident will be investigated and, if appropriate in the circumstances, charges laid. At the very least, the causing of incidental civilian deaths (even if technically permitted under IHL) will result in extensive criticism and widespread calls for transparent accountability for those responsible.
Much more discomfort emanates from the almost complete lack of transparency in the covert use of UCAV technology. Jane Mayer articulated the problem in her exposé of the CIA drone program. Mary Ellen O’Connell elsewhere in this issue explains that ‘[a]t least in Afghanistan ... the US use of drones has been justifiable so long as the rules governing battlefield conduct have been observed’. In her opinion, the real problem is what she characterises as the ‘seductive’ use of drone technology to inflict death in places geographically far removed from the battlefield in circumstances where previously no lethal force would have been used.
It seems that the Bush Administration strategically characterised its response to the 9/11 attacks as a (self-declared) ‘Global War on Terror’ in order to benefit from the permissive legal regime of IHL. IHL is permissive in the sense that it allows the deliberate targeting of combatants and also the incidental deaths of some civilians as ‘collateral’ damage. Outside of armed conflict (and the IHL legal regime), such deaths would best be characterised as extrajudicial killings, or murder. The characterisation of the Global War on Terror has continued under the Obama Administration which considers itself to be in an ‘armed conflict with al-Qaeda, as well as the Taliban and associated forces.’ The IHL legal framework is now generally used to justify drone attacks in geographic locations far removed from theatres of military operation. The legal requirement of an armed conflict as the condition precedent to the application of IHL as the relevant regulatory regime is conveniently overlooked. Instead, alleged terrorists, wherever they happen to be in the world, are apparently fair game and a hellfire missile fired from a CIA drone seems to be an acceptable means of dealing with them. This appeared to be the position taken by Harold Koh in an oft-cited speech delivered in 2010, in which he explained the legal basis for the US drone attacks, and the applicable legal principles governing such attacks.
There have, however, been some attempts to interpret Koh’s speech as ‘reaffirming’ and ‘reinvigorating’ the ‘traditional’ US view that national self-defence is the appropriate legal framework. Kenneth Anderson, for instance, has argued that IHL does not apply to targeted killings carried out by UCAVs. Indeed, Anderson has stated ‘in my understanding there is not technically speaking an “armed conflict” as such.’ Rather, he argues that these attacks are carried out as ‘self-defence’ and that therefore the customary laws that regulate the use of self-defence apply (these are distinct from, but similar to, the principles at the foundation of IHL).
Nevertheless, from an accountability perspective, the same problems remain regardless of which legal framework is applied. Because the CIA program is covert, there are no published policy guidelines, no certainty about the criteria for adding a name to a targeting list and no basis for knowing what, if any, scrutiny exists in relation to particular targeting decisions. Indeed, the US government still does not confirm or deny CIA targeted killing operations. As Gregory has put it, ‘the covert nature of a war conducted by a clandestine agency ensures that most of its victims are wrapped in blankets of secrecy.’ This state of affairs stands in stark contrast to the Israeli Supreme Court’s 2005 decision on targeted killings, which emphasised the importance of judicial oversight of targeted killings. As President Barak stated in that case:
It is our duty to preserve the legality of government, even when the decisions are difficult. Even when the cannons roar and the muses are silent, the law exists, and acts, and determines what is permissible and what is forbidden; what is legal and what is illegal. As the law exists, so exists the Court, which determines what is permissible and what is forbidden, what is legal and what is illegal.
There have been some attempts to secure judicial review of attacks that allegedly violated IHL. At the time of writing, for instance, a campaign led by British human rights lawyer, Clive Stafford Smith, is seeking an international arrest warrant for John Rizzo, who was formerly a general counsel for the CIA, and who recently admitted that he had approved one drone attack a month on targets in Pakistan. The warrant is sought for inter alia conspiracy for murder in relation to two attacks in 2009, one of which was carried out in the village of Machi Khel in North Waziristan. Lawyers are reportedly also ‘building cases against other individuals, including drone operators interviewed or photographed during organized press facilities.’ While attempts to initiate judicial scrutiny of the practice may please some, the difficulties involved in prosecuting alleged offences are obvious. In addition, any prosecution of ad hoc attacks carried out in Pakistan will not, in and of themselves, lead to a change in US policy to ensure the application of transparent accountability mechanisms to CIA targeted killing operations.
In addition to the concerns relating to the covert nature of drone attacks, the media and/or humanitarian NGO scrutiny that often exists in the theatre of military operations is regularly non-existent because CIA-authorised drone attacks occur in physical territory too remote for media or NGO access, or even in territory where such access is prohibited by the complicit territorial government authorities. For instance, in 2010 Rogers reported that the Pakistani government ‘tightly restricts access to most conflict-affected areas’; that access to Federally Administered Tribal Areas (FATA) is generally prohibited for foreigners; and that government permission ‘is required to visit Swat and other areas in Malakand.’ In addition, militant groups often target ‘foreigners as well as Pakistani journalists and NGO workers.’ As a result ‘there is very little independent, credible information emerging from areas under their control,’ and media reporters rely on ‘unnamed Pakistani intelligence officials.’
The covert nature of the drone attacks has had other ramifications for civilian victims. For instance Rogers, in a 2010 report on drone attacks in Northwest Pakistan, argued that the lack of transparency in the US drone program has also meant that civilian losses are largely ignored. He considered that neither US nor Pakistani authorities ‘have any standard, public procedures for investigating civilian losses from drone strikes, acknowledging or recognizing losses, or providing help for victims to recover.’ Although the Pakistan government provides compensation for civilian casualties, this reportedly does not extend to victims of drone strikes.
All these concerns were bought into sharp relief recently following a report in The Times that a US drone strike in Pakistan had killed two boys; 16-year-old Tariq Aziz and his 12-year-old cousin Waheed Khan. The boys were reportedly killed 72 hours after attending a tribal meeting on drone attacks, ‘where digital cameras donated by Jemima Khan ... were distributed to tribal leaders to enable them to record the effects of drone strikes.’ According to Stafford Smith, who was present at the meeting, Tariq stepped forward during the meeting and ‘volunteered to gather proof [of the drone strikes] if it would help to protect his family from future harm.’ Stafford Smith alleged that the boys were subsequently killed while driving to ‘pick up their aunt and bring her home to the village of Norak.’ The Pakistan media reported that ‘four militants’ were killed in the attack, citing ‘intelligence sources’. Aside from concerns over accuracy of attacks and accountability for violations of IHL, the report also contains an underlying suggestion that these boys may have been targeted due to erroneous intelligence, or worse, due to their involvement in the meeting. Of course, the accuracy of these reports is almost impossible to determine, as are the reasons why these boys were targeted; herein lies the source of controversy.
Mayer, O’Connell and others lament the apathy and indifference that prevails in response to the policy. The CIA continues its attacks and we know that those attacks are perpetrated beyond the scrutiny of the law, but there is little pressure on political authorities to cease and desist from the practice. Popular opinion supports the killing of ‘terrorists’ by whatever means available — particularly where the choice of means carries no harm to the side possessing the targeting technology. The widespread celebrations in the US following the assassination of Osama bin Laden demonstrate this proposition. Reports that an American citizen had been killed in a targeted killing in 2001 in Yemen, failed to generate significant public outcry. Similarly, reports in 2002 that a Predator had followed and killed three Afghan villagers collecting scrap metal, due to a mistaken belief that one of the men was Osama bin Laden, received very little media coverage. It will be interesting to see whether the killing by predator drone of US citizen Anwar Al-Awlaki in Yemen in September 2011 draws more public criticism in the US than earlier attacks. A spokesperson for the American Civil Liberties Union was quoted in response to the news of Al-Awlaki’s death by drone as claiming that: ‘This is a programme under which American citizens far from any battlefield can be executed by their own government without judicial process, and on the basis of standards and evidence that are kept secret not just from the public, but from the courts.’ Nevertheless, it is not clear that a sufficient number of US citizens will be outraged enough by the denial of judicial process in these circumstances to agitate for policy change.
It is difficult to contemplate the circumstances that might lead to a change in policy. At present there seems no prospect of electoral agitation against the use of drones. Perhaps policy change will only come as the decision-making elite faces the potentially devastating reality that there are no educated Taliban leaders left to negotiate with because a generation of senior and mid-ranking leaders have been eliminated by predators or reapers. Or, as Stafford Smith recently stated in response to the deaths of Tariq Aziz and Waheed Khan, ‘Tariq’s extended family, so recently hoping to be our allies for peace, has now been ripped apart by an American missile — most likely making any effort we make at reconciliation futile.’
The Nuclear Weapons Advisory Opinion indicates that absent a comprehensive treaty or customary prohibition on the use of a particular weapon, it is unlikely that its use will be illegal per se under international law. Whilst fundamental principles of IHL can theoretically render the use of a particular weapon illegal in all circumstances, the ICJ’s Advisory Opinion demonstrates that the threshold is very high. There is currently no treaty or customary prohibition on the use of UCVs, nor do these weapons inherently contravene any of the basic principles of IHL, such as the obligation to distinguish or the prohibition on causing unnecessary suffering. As such, there is no prohibition on UCVs under international law, although their use in armed conflict must always be consistent with general principles of IHL.
The 1995 treaty prohibition on blinding laser weapons was unusual because the overwhelming majority of states agreed to a comprehensive prohibition before the technology had been deployed to any significant extent on the battlefield. Presumably no state wanted to bring home combatants who had been permanently blinded, and so there was a unique level of multilateral commitment to ban the technology. More often, however, weapons are deployed extensively on the battlefield before they become the subject of a specific treaty ban. There will often be some general or particular catalyst for a specific treaty ban — such as deleterious humanitarian consequences from widespread deployment of the weapons in disregard for the affected civilian population. In the case of anti-personnel landmines the catalyst was a general one — the sheer magnitude of the problem of unexploded landmines causing horrific injuries for decades after the cessation of hostilities drove the campaign for a specific treaty ban. In the case of cluster munitions, there had also been growing calls for prohibition from repeated humanitarian disasters, but the particular deployment of large numbers of dud submunitions in Southern Lebanon constituted a notable impetus for a specific treaty prohibition. In the case of both anti-personnel landmines and cluster munitions there was substantial public outcry, as well as a growing perception that general rules of IHL were manifestly not sufficient on their own to regulate the use of these weapons.
UCAVs have been used by military forces, most notably the US military, in armed conflict situations since 2001. This use has generated little controversy, aside from those who have expressed concern about the future directions of this technology — most notably the prospect of fully autonomous weapons operating in the battlefield.
In contrast, the covert drone targeted killings program operated by the CIA gives rise to serious concerns, and has been roundly criticised by a number of commentators. Nevertheless, there has been comparatively little public outcry over these killings. The reasons for this are generally unclear. The lack of outcry may be a result of little public sympathy for ‘terrorists’. Perhaps it also results from the difficulties associated with monitoring and investigating covert operations carried out by drones. The geographic location of drone strikes inevitably means that the media and humanitarian NGOs are unlikely to be able to investigate and report on, let alone witness, individual attacks. In addition, it is unlikely that any military personnel (or CIA operatives) are physically present at the scene to witness the effects of a strike. Thus the only US witnesses are likely to be those from the CIA, watching the strike on screens thousands of miles from the scene of the attack. This, combined with the lack of any judicial body that reviews targeting decisions and publishes its findings, means it is very difficult for the public to accurately assess the effects of these strikes, or their compliance with IHL.
The question asked at the outset of this paper was whether general principles of IHL are sufficient to regulate the use of UCAVs. This paper has sought to argue that the weapons themselves can be, and indeed often are, used in conformity with IHL. However, it is difficult, if not impossible, to ensure that IHL is respected without consistent monitoring of attacks, investigation of potential breaches, some form of judicial review of decisions made and accountability for violations of the law. Indeed, even as early as 1949, the Geneva Conventions recognised the importance of accountability, and recent years have seen an increasing push towards transparent processes and accountability for violations of IHL by responsible civilian and military leaders. In this regard at least, the covert CIA targeted killing program represents a retrograde step.
[*] Tim McCormack is an Adjunct Professor of Law at the University of Tasmania and is the Special Adviser on International Humanitarian Law to the Prosecutor of the International Criminal Court in The Hague. The views expressed in this article are those of the authors alone.
 Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion)  ICJ Rep 226,  (‘Nuclear Weapons Advisory Opinion’).
 See, for example, various articles analysing the Nuclear Weapons Advisory Opinion and discussing its implications in the symposium issue of (1997) 316 International Review of the Red Cross.
 General and Complete Disarmament, GA Res 49/75, 90th plen mtg, UN Doc A/Res/49/75 (1994).
 Nuclear Weapons Advisory Opinion,  ICJ Rep 226.
 Ibid .
 Ibid .
 Ibid .
 Ibid -.
 Ibid .
 Ibid .
 Treaty on the Non-Proliferation of Nuclear Weapons, opened for signature 1 July 1968, 729 UNTS 161 (entered into force 5 March 1970) (‘NPT’).
 Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their Destruction, opened for signature 10 April 1972, 1015 UNTS 163 (entered into force 26 March 1975) (‘Biological Weapons Convention’).
 Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction, opened for signature 13 January 1993, 1974 UNTS 45 (entered into force 29 April 1997) (‘Chemical Weapons Convention’).
 NPT, Articles I and II. For more detail on the NPT as a comprehensive treaty ban for the overwhelming majority of States Parties, see T McCormack, ‘A Non-Liquet on Nuclear Weapons: The ICJ Avoids the Application of General Principles of International Humanitarian Law’ (1997) 316 International Review of the Red Cross 76.
 See for instance: Implementation of the NPT Safeguards Agreement in the Islamic Republic of Iran, International Atomic Energy Agency Board of Governors, Resolution Adopted 4 February 2006 (Gov/2006/14); Implementation of the NPT Safeguards Agreement and Relevant Provisions of Security Council Resolutions 1737 (2006), 1747 (2007), 1803 (2008) and 1835 (2008) in the Islamic Republic of Iran, International Atomic Energy Agency Board of Governors, Resolution Adopted 27 November 2009 (Gov/2009/82); SC Res 1747, UN SCOR, 5647th mtg, UN Doc S/Res/1747 (24 March 2007); SC Res 1803, UN SCOR, 5848th mtg, UN Doc S/Res/1803 (3 March 2008); SC Res 1835, UN SCOR, 5984th mtg, UN Doc S/Res/1835 (27 September 2008); SC Res 1929, UN SCOR, 6335th mtg, UN Doc S/Res/1929 (9 June 2010).
 SC Res 825, UN SCOR, 3212th mtg, UN Doc S/Res/825 (11 May 1993); Implementation of the NPT Safeguards Agreement Between the Agency and the Democratic People’s Republic of Korea, International Atomic Energy Agency General Conference Resolution adopted on 20 September 2002 (GC(46)/RES/14); Implementation of the NPT Safeguards Agreement Between the Agency and the Democratic People’s Republic of Korea, International Atomic Energy Agency General Conference Resolution adopted 19 September 2003 (GC(47)/RES/12). For an overview of North Korea’s conduct with respect to the NPT, see: Application of Safeguards in the Democratic People’s Republic of Korea, Report by the Director General of the International Atomic Energy Agency to the Board of Governors and General Conference, (2 September 2011, GOV/2011/53-GC(55)/24).
 SC Res 1695, UN SCOR, 5490th mtg, UN Doc S/Res/1695 (15 July 2006); SC Res 1718, UN SCOR, 5551st mtg, UN Doc S/Res/1718 (14 October 2006); SC Res 1874, UN SCOR, 1874th mtg, UN Doc S/Res/1874 (12 June 2009).
 Treaty on the Non-Proliferation of Nuclear Weapons, opened for signature 1 July 1968, 729 UNTS 161 (entered into force 5 March 1970) Article IX(3).
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, -.
 Ibid .
 Ibid. See the Court’s decision at  (human rights law),  (genocide) and  (environmental protection law).
 Ibid -, .
 Ibid .
 Ibid .
 For instance, Hague Convention (IV) Respecting the Laws and Customs of War on Land and Its Annex: Regulations Concerning the Laws and Customs of War on Land, adopted 18 October 1907 (entered into force 26 January 1910); Geneva Convention (I) for the Amelioration of the Condition of Wounded and Sick in Armed Forces in the Field, opened for signature 12 August 1949, 75 UNTS 85 (entered into force 21 October 1950); Geneva Convention (II) for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, opened for signature 12 August 1949, 75 UNTS 85 (entered into force 21 October 1950); Geneva Convention (III) Relative to the Treatment of Prisoners of War, opened for signature 12 August 1949, 75 UNTS 135 (entered into force 21 October 1950); Geneva Convention (IV) Relative to the Protection of Civilian Persons in Time of War, opened for signature 12 August 1949, 75 UNTS 287 (entered into force 21 October 1950). Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts, opened for signature 12 December 1977, 1125 UNTS 3 (entered into force 7 December 1979) (‘Additional Protocol I’).
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, .
 Ibid  (Dissenting Opinion of Judge Higgins).
 Ibid , quoting the written statement from New Zealand. See also Dissenting Opinion of Judge Weeramantry at 444.
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, .
 Ibid .
 Ibid 403 (Dissenting Opinion of Judge Shahabuddeen).
 Ibid. See also, International Declaration Respecting Expanding Bullets, signed at The Hague, 29 July 1899 (entered into force 4 September 1900).
 Additional Protocol I; Hague Convention (IV) Respecting the Laws and Customs of War on Land and Its Annex: Regulations Concerning the Laws and Customs of War on Land, adopted 18 October 1907 (entered into force 26 January 1910).
 Jean-Marie Henckaerts and Louise Doswald-Beck, Customary International Law, Volume I: Rules (Cambridge University Press, 2005) 237.
 Rome Statute of the International Criminal Court, opened for signature 17 July 1998, 2187 UNTS 90 (entered into force 1 July 2002). See Article 8(2)(b)(xx) in the context of an international armed conflict.
 See for instance the submissions of France and Russia to the ICJ in the Nuclear Weapons case: ‘Written Statement and Comments of the Russian Federation on the Issue of the Legality of the Threat or Use of Nuclear Weapons’, Submission in Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, 19 June 1995, 13; French submission cited in Henckaerts and Doswald-Beck, above n 37, 243.
 For instance, Colonel Hays Parks, formerly of the US military, has stated several times in public fora that when he was responsible for the legal review of proposed new weapons systems at the Pentagon he personally refused to authorise a number of proposed new systems on the basis that he believed they would violate the customary prohibition. (Tim McCormack’s recollections on Hays Parks’ comments at a number of IHL and weapons conferences).
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, .
 Ibid .
 Convention II with Respect to the Laws and Customs of War on Land and Its Annex: Regulation Concerning the Laws and Customs of War on Land, adopted 29 July 1899 (entered into force 4 September 1900), Preamble. See also Hague Convention (IV) Respecting the Laws and Customs of War on Land and Its Annex: Regulations Concerning the Laws and Customs of War on Land, adopted 18 October 1907 (entered into force 26 January 1910) Preamble.
 Additional Protocol I, Article 1(2).
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, .
 See, for instance ‘Written Statement and Comments of the Russian Federation on the Issue of the Legality of the Threat or Use of Nuclear Weapons’, Submission in Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, 19 June 1995, 13; ‘Letter Dated 16 June 1995 From the Legal Adviser to the Foreign and Commonwealth Office of the United Kingdom of Great Britain and Northern Ireland, together with Written Comments of the United Kingdom’, Submission in Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, 16 June 1995, 3.58.
 See Rupert Ticehurst, ‘The Martens Clause and the Laws of Armed Conflict’ (1997) 317 International Review of the Red Cross; Antonio Cassese, ‘The Martens Clause: Half a Loaf or Simply Pie in the Sky?’ (2007) 11(1) European Journal of International Law 187, 191, doi: 10.1093/ejil/11.1.187.
 Prosecutor v Kupreskic et al (Judgment) (International Criminal Tribunal for the Former Yugoslavia, Trial Chamber II, Case No IT-95-16-T-14, 14 January 2000) § 525.
 Theodor Meron, ‘The Martens Clause, Principles of Humanity, and Dictates of Public Conscience’ (2000) 94(1) American Journal of International Law 78, 88.
 Additional Protocol I, Article 48.
 Ibid, Article 51(2) and (4).
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226, .
 Ibid .
 Ibid .
 Ibid .
 See, for example, McCormack, above n 14, 91.
 On these agreements, see Missile Technology Control Regime, Introduction <http://www.mtcr.info/english/index.html> and Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies (‘Wassenaar Arrangement’), Introduction (3 November 2011)
 See generally, Missile Technology Control Regime, Objectives of the MTCR <http://www.mtcr.info/english/index.html> .
 Wassenaar Arrangement, Introduction (3 November 2011)
 Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Elimination of Their Intermediate-Range and Shorter-Range Missiles, signed 8 December 1987, 27 ILM 183 (entered into force 1 June 1988) (‘INF Treaty’). The US Department of Defence suggested in 2001 that the development of UCAVs would need to comply with the INF Treaty. See US Office of the Secretary of Defence, Unmanned Aerial Vehicles Roadmap 2000-2025, (April 2001) Section 6.4.3 Treaty Considerations; Laurence R Newcome, Unmanned Aviation: A Brief History of Unmanned Aerial Vehicles (American Institute of Aeronautics and Astronautics, 2004) 6; Dennis Gormley and Richard Speier, Controlling Unmanned Air Vehicles: New Challenges (19 March 2003) Paper Commissioned by the Non-Proliferation Education Center <cns.miis.edu/npr/pdfs/102gorm.pdf>.
 Treaty on Conventional Armed Forces in Europe, signed 19 November 1990, 30 ILM 1 (entered into force 17 July 1992). See Jurgen Altmann, ‘Preventive Arms Control for Uninhabited Military Vehicles’ (2009) Ethics and Robotics 69; Laurence R Newcome, Unmanned Aviation: A Brief History of Unmanned Aerial Vehicles (American Institute of Aeronautics and Astronautics, 2004) 6; Gormley and Speier, above n 60, 7.
 Peter Singer, ‘Robots at War: The New Battlefield’ (2009) 33(1) Wilson Quarterly 30, 31-32.
 Noel Sharkey, ‘Saying “No!” to Lethal Autonomous Targeting’ (2010) 9(4) Journal of Military Ethics 369, 370, <http://dx.doi.org/10.1080/15027570.2010.537903> Ibid.
 See Roy Braybrook, ‘Strike Drones: Persistent, Precise and Plausible’ (2009) 33(4) Armada International 21, 21; United Kingdom Ministry of Defence, Joint Doctrine Note 2/11, The UK Approach to Unmanned Aircraft Systems (30 March 2011) <http://www.mod.uk/DefenceInternet/MicroSite/DCDC/OurPublications/JDNP/Jdn211TheUkApproachToUnmannedAircraftSystems.htm> .
 Philip Alston, Interim Report of the Special Rapporteur on Extrajudicial, Summary or Arbitrary Executions, UN Doc A/65/321 (23 August 2010) .
 William H Boothby, Weapons and the Law of Armed Conflict (Oxford University Press, 2009) 230.
 Human Rights Watch, Precisely Wrong: Gaza Civilians Killed by Israeli Drone-Launched Missiles (30 June 2009), 4
 United Nations Human Rights Council, Human Rights in Palestine and Other Occupied Arab Territories, Report of the United Nations Fact-Finding Mission on the Gaza Conflict, A/HRC/12/48 (24 September 2009) 985.
 Michael N Schmitt, ‘Drone Attacks Under the Jus ad Bellum and Jus in Bello: Clearing the Fog of Law’ (2010) 13 Yearbook of International Humanitarian Law 311, 321 doi: 10.1007/978-90-6704-811-8_9.
 Nuclear Weapons (Advisory Opinion),  ICJ Rep 226,  (Dissenting Opinion of Judge Higgins); HCJ 769/02, The Public Committee against Torture in Israel v The Government of Israel (11 December 11 2005) 42-43.
 HCJ 769/02, The Public Committee against Torture in Israel v The Government of Israel (11 December 11 2005) 42; Prosecutor v Kupreskic et al (Judgment) (International Criminal Tribunal for the Former Yugoslavia, Trial Chamber II, Case No IT-95-16, 14 January 2000).
 Boothby, above n 66, 79.
 HCJ 769/02, The Public Committee against Torture in Israel v The Government of Israel (11 December 2005).
 Human Rights Watch, above n 67, 4.
 HCJ 769/02, The Public Committee against Torture in Israel v The Government of Israel (11 December 2005) 8.
 Ibid 21.
 Ibid 60.
 Ibid 46.
 For an overview of the current state of UV technology, and the potential for autonomy, see Sharkey, above n 63; Singer, above n 62, 36; Alston, above n 65; United Kingdom Ministry of Defence, above n 64, 5-4.
 Sharkey, above n 63, 376.
 United Kingdom Ministry of Defence, above n 64, 5-4.
 Ibid 5-10.
 United States Air Force, Unmanned Aircraft Systems Flight Plan 2009-2047 (18 May 2009), 41 <http://www.fas.org/irp/program/collect/uas_2009.pdf> .
 Sharkey, above n 63, 369.
 Ibid 380.
 Ibid 379.
 Alston, above n 65, ; See also Singer, above n 62, 36.
 Additional Protocol I, Article 36.
 See Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on Their Destruction, opened for signature 3 December 1997, 2056 UNTS 211 (entered into force 1 March 1999); Convention on Cluster Munitions, opened for signature 3 December 2008 (entered into force 1 August 2010).
 Tim McCormack, Sarah Finnin and Paramdeep Mtharu, International Humanitarian Law and Explosive Remnants of War: Report on States Parties’ Responses to the Questionnaire, presented to the Group of Governmental Experts’ Working Group on Explosive Remnants of War of the States Parties to the 1980 Certain Conventional Weapons Convention (United Nations, March 2006) 49.
 See Human Rights Watch, Flooding South Lebanon: Israel’s Use of Cluster Munitions in Lebanon in July and August 2006 (16 February 2008)
 Ibid 44-48.
 John Borrie, ‘The “Long Year”: Emerging International Efforts to Address the Humanitarian Impacts of Cluster Munitions, 2006-2007’ (2007) 10 International Yearbook of International Humanitarian Law 251, 259.
 See generally, ibid; Nout van Woudenberg, ‘The Long and Winding Road Towards an Instrument on Cluster Munitions’ (2008) 12(3) Journal of Conflict and Security Law 447.
 Jane Mayer, ‘The Predator War: What Are the Risks of the CIA’s Covert Drone Program?’ The New Yorker (New York) 26 October 2009. For a comprehensive criticism of the CIA’s drone program, see Philip Alston, ‘The CIA and Targeted Killing Beyond Borders’ (Working Paper No. 11-64, New York University School of Law, Public Law and Legal Theory Research Paper Series, 2011).
 Mary Ellen O’Connell, ‘Seductive Drones: Learning from a Decade of Lethal Operations’ (2011) 21(2) Journal of Law, Information and Science, EAP 10, doi: 10.5778/JLIS.2011.21.OConnell.1.
 Ibid 26-27.
 See Harold Koh, ‘The Obama Administration and International Law’ (Speech delivered at the Annual Meeting of the American Society of International Law, Washington, DC, 25 March 2010)
 The application of IHL to the ‘war on terror’ has been widely criticised. See Gabor Rona, ‘Legal Frameworks to Combat Terrorism: An Abundant Inventory of Existing Tools’ (2004-2005) 5 Chicago Journal of International Law 499, 505; Human Rights Watch, ‘Targeted Killings and Unmanned Combat Aircraft Systems (Drones)’ (7 December 2010) open letter to President Barack Obama <http://www.hrw.org/sites/default/files/related_material/Letter%20to%20President%20Obama%20-%20Targeted%20Killings%20(1).pdf> But for an analysis of the application of IHL to the CIA program see Ian Henderson, ‘Civilian Intelligence Agencies and the Use of Armed Drones’ (2010) 13 Yearbook of International Humanitarian Law 133.
 Codified in, for instance, common article 2 of the four Geneva Conventions.
 Koh, above n 101.
 Kenneth Anderson, ‘Drones II’ Testimony submitted to US House of Representatives Committee on Oversight and Government Reform, Subcommittee on National Security and Foreign Affairs, Second Hearing on Drone Warfare, 28 April 2010, 13,15.
 Ibid 14.
 Ibid footnote 6.
 Ibid 14.
 See Human Rights Watch, above n 102, 4.
 See Anderson, above n 105, 20.
 Derek Gregory, ‘The Everywhere War’ (2011) 177(3) Geographical Journal 238.
 HCJ 769/02, The Public Committee against Torture in Israel v The Government of Israel (11 December 2005) 61-64.
 HCJFH 2161/96, Sharif v GOC Home Front Command, 50(4) PD 485, 491. Cited in ibid, 63.
 Peter Beaumont, ‘Campaigners Seek Arrest of Former CIA Legal Chief Over Pakistan Drone Attacks’, The Guardian (London) 15 July 2011.
 According to Rogers, the majority of drone strikes in Pakistan occur in North and South Waziristan, areas that are inaccessible to foreigners and most Pakistanis. See Christopher Rogers, ‘Civilian Harm and Conflict in Northwest Pakistan’ (2010) Report for the Campaign for Innocent Victims in Conflict (CIVIC), Civilians in Armed Conflict Series, 14
 Ibid 13. See also Mayer, above n 98; and Beaumont, above n 114.
 Rogers, above n 117, 13.
 Saeed Shah and Peter Beaumont, ‘US Drone Strikes in Pakistan Claiming Many Civilian Victims, Says Campaigner’, The Guardian (London) 17 July 2011.
 Rogers, above n 117, 62-64.
 Ibid 63.
 Ben MacIntyre, ‘”Boys” Killing Belies US Claim on Drone Strikes’, The Times (London) 5 November 2011.
 Clive Stafford Smith, ‘For Our Allies, Death From Above’, New York Times (New York) 3 November 2011.
 MacIntyre, above n 125.
 See Mary O’Connell, ‘Unlawful Killing with Combat Drones: A Case Study of Pakistan, 2004-2009’ (Research Paper No 09-43, Notre Dame Law School Legal Studies, 2009) in Simon Bronitt (ed), Shooting To Kill: The Law Governing Lethal Force In Context (Forthcoming) 3.
 See Mayer, above n 98.
 Martin Chulov and Paul Harris, ‘Anwar al-Awlaki, al-Qaida Cleric and Top US Target, Killed in Yemen’, The Guardian (online), 30 September 2011, quoting ACLU deputy legal director Jameel Jaffer
 Clive Stafford Smith, ‘For Our Allies, Death From Above’, New York Times (3 November 2011).
 Additional Protocol to the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons which May be Deemed to be Excessively Injurious or to have Indiscriminate Effects (Protocol IV, entitled Protocol on Blinding Laser Weapons), opened for signature 13 October 1995, 1380 UNTS 370 (entered into force 30 July 1998).
 See, for example, the 2006 report by Landmine Action, The Failure to Protect: A Case for the Prohibition of Cluster Munitions (2011)
 See Geneva Convention (I) for the Amelioration of the Condition of Wounded and Sick in Armed Forces in the Field, opened for signature 12 August 1949, 75 UNTS 85 (entered into force 21 October 1950) Article 49.