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Armed Drones: Legal Issues from an International Law Perspective

Since President Obama took office, the sharp increase in the use of armed drones (or unmanned aerial vehicles – UAVs) against members of the Al-Qaeda terrorist organization and Taliban fighters in Afghanistan and north-western Pakistan (but also against militants in Somalia and Yemen) has triggered a broad public debate on the issues surrounding armed drone usage. This debate has been particularly explosive in Germany. While many Germans find it generally difficult to accept the targeted killing of enemy combatants (not to mention civilians), killing by machines (such as armed drones) makes them particularly uneasy. Politically, this unease has found expression in reactions to suggestions that the German armed forces should themselves consider acquiring armed drones. From the military standpoint, the case for armed drones is clear: If reconnaissance drones are able through electronic surveillance to detect enemy activity that could pose considerable danger to German military personnel and equipment, it makes sense to deal with that threat immediately in real-time. And the only feasible way to engage in real-time combat is to launch guided missiles directly from the drones.

Despite these military reasons for the deployment of armed drones, large sections of the public remain skeptical – as do specialists in law, social ethics and political science. Normative considerations appear to militate against the use of armed drones. But what sources substantiate these normative grounds? At any rate not positive international law – as this article will briefly explain below. International Humanitarian Law (IHL) does not prohibit the use of armed drones. It does impose certain restrictions, but these apply equally to the deployment of the guided missiles in other operational contexts, for example the deployment of such guided missiles from warplanes and helicopters. In-depth analysis shows that the problem resides behind the norms of positive international law, at another level of normative judgment; at best it can be exemplified with (social ethics) principles on which IHL and its rules on methods and means of warfare are based. That is not to say, however, that there are no good reasons for a healthy dose of normative skepticism regarding the “normalization” of armed drone usage.

Armed drones in International Humanitarian Law

One basic problem from an international law perspective regarding the phenomenon of armed drones is the fact that the drones themselves are not weapons, or ordnance, in the technical sense, but rather in terms of basic principles solely an (unmanned) military aircraft that serves as a weapon platform. IHL law only governs weapons, not weapon platforms. The drone as a military object is clearly a legitimate military target, but only the guided munitions which are carried and directed to their targets by the drones are the object of regulation of the norms of IHL concerning means and methods of warfare. In turn, the types of guided munitions in question are not specific to drones and are used on other aircrafts as well, such as fighter jets and military helicopters. In these applications they have largely been regarded as unproblematic. Yet growth in the scope of deployment to include drone usage in no way changes the effects of weapons with which IHL is concerned. Does this mean that armed drone missions are unproblematic per se? Things are not quite that simple. What causes unease is ultimately not the weapon platform or the guided missile as a weapon, but rather the typical deployment scenario for armed drones, which constitute an archetypal military technology of asymmetrical conflict. Under such circumstances, the guided missile directed to its target from drones is in effect a radical type of distance weapon. There is only a very fine difference compared to firing an artillery shell from a distance or launching a cruise missile. Particularly in situations when a reconnaissance drone observes and marks the target, the boundaries between the different types of use are blurred. And yet there are discernible differences. Artillery has a limited range, and a suitable battery has to be sufficiently close by and ready to fire, if distance combat – with any kind of mobile target – is to be successful. The same applies to the deployment of warplanes. Only an armed drone is capable of fighting an identified military target immediately, in real-time.

Military targets in asymmetrical conflicts are frequently gatherings of enemy combatants. However – and this is one of the characteristics of asymmetrical conflicts – these are usually not clearly distinguishable from the general civilian population. From a purely legal point of view, “irregular” fighters in non-international armed conflicts are members of the civilian population. Although they lose their protection if they directly participate in fighting, the problem of differentiation remains. This differentiation problem is negligible if a patrol or combat unit encounters and opens fire on a group of enemy combatants. Things become more complicated when using distance weaponry. If I come to the assistance of a patrol caught in an ambush with artillery fire or “close air support”, the situation remains relatively simple. The problem of making a clear distinction becomes more tricky, however, if I want to use distance weaponry against suspected enemy combatants – i. e. actively launch an attack against a supposedly or actually identified opponent. The fact that targeted persons are carrying or firing weapons without enemy engagement doesn’t count for much in contexts such as Afghanistan, Yemen and Somalia – one is reminded of cases where wedding parties were accidentally obliterated following ritual celebrations with the small arms that are socially customary in such places. The narrower the time window between identifying the (supposed) military target and the use of weapons, the greater the risks of misjudgment, distorted perception or a sudden change in circumstances that the military actor taking the decision is unaware of. As an example, one needs to think only of the infamous Kunduz incident, in which a tragic error of judgment led to an airstrike on two captured tanker trucks with substantial loss of civilian life.

Unease over the use of armed drones becomes confused here with the debate on the issue of targeted killing. Targeted killing of military opponents who are fighting against you with a weapon in their hand is unproblematic. According to prevailing opinion, the concept of direct participation also extends to professional combatants who as part of an organized military apparatus fully devote their time and energy to fighting the enemy, including the political leaders of such military apparatuses. Part-time combatants, on the other hand, who only occasionally retrieve their weapons from their hiding places, but otherwise lead an inconspicuous civilian life as farmers or artisans, are protected as members of the civilian population – unless they are found with a weapon in their hand.

Further problems arise with regard to “collateral casualties”, which are virtually inevitable to some extent in military operations. We don’t know how many women, children and innocent civilians have been killed by American drone strikes. We only know that the numbers are considerable – and in the context of operations in Afghanistan and Pakistan this is hard to avoid, if we do not refrain entirely from strikes on targets in human settlements or vehicle convoys, where protected civilians are found alongside enemy combatants. The problem of the legitimacy of such collateral casualties is highly complex and an in-depth examination is beyond the scope of this article. In principle, though, it is no different from the collateral casualty problem with conventional air or artillery strikes.

The legitimacy of targeted killings outside of armed conflict settings is an extremely difficult question. Human rights guarantees apply here. Targeted killings – according to the rules concerning the use of police force which are applicable in this respect – are allowed only in extreme cases of direct self-defense or emergency assistance in the event of an acute threat to the lives of task forces or innocent bystanders. This almost completely rules out the (military) use of armed drones.

The limits of military force from an ethical perspective

Yet these considerations of positive international law have not yet really touched on the actual problem of social ethics that is responsible for most of the unease regarding armed drones. Aversion to radicalized distance weaponry, which is what armed drones turn out to be, is not really fueled by the problems of targeted killing and collateral casualties. Instead, it has to do with the basic models of ethical justification for killing in war, which no longer seem so sound in the case of drones. As a soldier, I can target and kill the enemy, because I am - ultimately - engaged in a kind of institutionalized self-defense. Even if my own life is not in danger from possible enemy fire – which is unlikely to be the case with distance weaponry – I am allowed to fight the enemy where I find him, as otherwise he will direct his force against my fellow soldiers, whom I am to protect in solidarity against the adversary. The foundation of this legitimacy on social ethics principles generally becomes rather shaky in “asymmetrical” conflicts. With the use of armed drones, however, this model of justification finally reaches its limits.

This becomes particularly apparent in the circumstances surrounding drone strikes in Pakistan, which on the American side are controlled by CIA civilian personnel. The persons involved are not in any danger themselves (not even potentially), nor do they have any kind of fellowship or ties of solidarity with the U.S. army soldiers whose lives are being protected in Afghanistan. For the agent taking action, the targeted use of deadly weapons increasingly mutates into a kind of computer game which bears no resemblance to armed confrontation (that carries risks). This causes two problems: the problem of perceptual shortcomings that occur with drastically reduced decision-making time, and the problem of ethical desensitization. Exploiting the military advantages of real-time military action demands short decision-making processes and the ability to make an immediate decision on the spot. As a result, there are no more long chains of command with legal counsel. The decision must be taken immediately, otherwise the advantage of the drone is lost. In this activity loop of (perhaps only supposedly) identifying a military target with the expectation of immediate response, all forms of perceptual distortion and bias that humans bring to such situations inevitably come into play. One is no longer directly confronted with the consequences of using force (as opposed to a soldier in conventional combat, who might subsequently discover he mistakenly shot a harmless civilian). This complete separation from the problematic consequences of using force ultimately leads to ethical desensitization, such as we can observe in psychological research in relation to typical violent computer games. Just as it is difficult for conventional soldiers in the field to overcome their intuitive inhibition to kill and to avoid that the crises of conscience caused by witnessing the consequences of force lead to post-traumatic stress disorder, the same way it is easy for drone operators to distance themselves from acts of violence.

This is all the more unfortunate given that central regulatory provisions of IHL – particularly with regard to the problem of collateral casualties – appeal to the ethical judgment of military decision-makers. The decision of conscience that is required in balancing the expected military advantage with the likely collateral casualties ultimately relies on the ethical sensibility of the military person responsible for taking action or making the decision to act – and indeed, such a decision of conscience crushed many soldiers and officers when facing it . The almost complete disburdening of active personnel as regards this kind of crisis of conscience may be “efficiency boosting” for bureaucratic military apparatuses, but in essence it undermines the foundations of the way in which the rules of IHL law operate.

This is particularly obvious in the practice of signature strikes, where the operational decision is routinized with respect to particular combinations of factors – and it is taken to extremes in scenarios where autonomously operating machines automatically respond to particular detection patterns with a signature strike. The active subject, equipped with a conscience, is relieved of all responsibility here, while the ethically wrong decision (which is still possible) is invisibilized in the anonymous program codes of the drones’ control software. In fact, no individual person is legally responsible anymore; what we are left with is the collective responsibility of the military apparatus, which is difficult to pinpoint. The military apparatus, meanwhile, has no conscience and is also unable to conduct an ethically responsible balancing of conflicting interests. But at this point we once again have a problem for positive international law – International Humanitarian Law absolutely requires military decision-makers to take personal responsibility for the balancing of conflicting interests.



Stefan Oeter studied jurisprudence and political science in Heidelberg/Montpellier 1979-1983. After his time as trainee lawyer, he was a research consultant at Max Planck Institute for Comparative Public Law and Int. Law in Heidelberg (1987-1999). In 1990, he became Dr. iur. at Heidelberg and received his habilitation in 1997. Since 1999: professor of German and Comparative Public Law and Int. Law, Managing Director of the Institute of Int. Affairs at Hamburg University. He is a German member of the independent Committee of Experts of the European Charter for Regional or Minority Languages of the European Council (chairman 2006-2013); chairman of the Historical Commission of the Int. Society for Military Law and the Law of War; member of the Permanent Court of Arbitration, The Hague. Main research fields: comparative federalism, protection of linguistic and cultural minorities, int. humanitarian law, Europ. and int. economic law, and theory of int. law and int. relations.