Required knowledge: Public International Law/Sources of International Law, Public International Law/Human Rights Law, Public International Law/Use of Force

Learning objectives: Understanding the law of armed conflict (jus in bello) in light of its historical roots and today's current challenges.

A. General introduction to the law of armed conflict Edit

There has not been a phenomenon as consistent as violence and conflict in the world. The persistence of conflicts gave way to efforts to regulate it, first in terms of regulating weapons as in the (euro-centric) 1868 St. Petersburg Declaration, and later on by specifically protecting civilians and the civilian population from the conduct of hostilities in the four universal Geneva Conventions and their additional protocols (often described as "international humanitarian law"). Rules and principles to limit the harm to civilian objects and the civilian population were present as early as the recorded human history. The content of these rules and principles was (and is) not purely humanitarian. There is a constant struggle with balancing military necessities with humanitarian aims. Warfare has always been cruel and brutal, yet the effect of such a regulation is often also humanitarian in terms of limiting human suffering.[1] For instance, an ancient African rule prohibits the poisoning of wells (similar to the 1899/1907 Hague Regulations), this prohibition also protects the civilian population and contributes to its survival since water is existential, thus serving a humanitarian motive. The jus in bello (another synonym for law of armed conflict) should not be mixed with the jus ad bellum (or jus contra bellum), which refers to the prohibition of the use of force and its exceptions. Even though aggression is prohibited (see Art. 2(4) UN Charter), the law of armed conflict includes rules and principles regulating how an armed conflict can be conducted lawfully. Questions on whether an aggression was justified are understood separately from the laws of armed conflict; both parties to a conflict are bound to the same extent, notwithstanding legal questions on the legality of the initial aggression.

This chapter begins with a historical overview to better understand the origins of the law of armed conflict (B.). It then turns to the classification of a conflict, which determines the specific legal framework in the law of armed conflict that regulates the specific conduct of hostilities (C.). Afterwards, the relevance of customary international law is highlighted by reference to the core principles of the law armed conflict (D.). Actors in the law of armed conflict are briefly described (E.), leading to current challenge within the law of armed conflict (F.). The chapter concludes with a brief summary on how the law of armed conflict can interact with other fields of public international law (E.).

B. Historical overview Edit

Modern law of armed conflict emerges as a result of historical norms and traditions. The terrible harm witnessed by Henry Dunant[2] after the battle of Solferino in 1859 serves as a catalyst for this development.[3] Parallel to states coming together to regulate a further warfare escalation with new weapons emerging in the 19th century, influential figures of the peace movement, such as Dunant or Bertha von Suttner,[4] campaign to adopt regulations to limit the suffering of the wounded. The creation of the International Committee of the Red Cross (ICRC) in 1863, the first Geneva Convention for the Amelioration of the Condition of the Wounded in Armies in the Field of 1864, and eventually also the 1899/1907 Hague Regulations aim at protecting the wounded in wars. At the beginning, 16 states from mainly Europe and Latin America participate in the first Geneva Conference, which results in an agreement on principles that emphasises the care for wounded individuals on the battlefield, regardless of their nationality. Later on, the Hague Peace Conferences further expands the regulations and also includes rules governing naval warfare. These rules are subsequently confirmed and amended in the four 1949 Geneva Conventions.

The 19th century regulation as well as the 1899/1907 Hague Regulations can neither stop two world wars (and did not intend to do so), nor were they able to prevent all human suffering. The two world wars and their devastating consequences for the civilian population, however, underscore the need for universally applicable rules and regulations to curtail the horrendous character of modern warfare. Consequently, diplomatic conferences are held to agree on rules to care for the sick, wounded, and prisoners of war. These conferences also intend to expand the scope of earlier conventions. They enshrine rules on the protection of civilian populations in times of war as well as under foreign occupation, and generally regulate international armed conflicts. Their common Art. 3 addresses non-international armed conflicts.[5] The Vietnam War among others highlights the need for further warfare regulation, consequently the two Additional Protocols from 1977 contain address colonial wars. While AP II focuses on non-international armed conflicts and includes a set of rules applying to conflicts between states and non-state actors, AP I contains rules that extend the protection of the four Geneva Conventions. Art. 1(4) AP I, for instance, emphasises that situation in which peoples fight against colonial domination, alien occupation or racist regimes are considered international armed conflicts, and Art. 8-34 AP I extend the protection of the Geneva Conventions to civilian medical personnel, equipment and supplies and to civilian units and transports.

C. Classification of an armed conflict Edit

As the starting point when analysing a specific armed conflict, first one has to determine what kind of armed conflict is taking place to identify the relevant legal framework that applies. This so-called classification[6] refers to two categories of conflict: an international armed conflict (IAC) and a non-international armed conflict (NIAC). IACs between two or more states are regulated by the four Geneva Conventions and AP I (as well as by custom), while NIACs between a state and a non-state actor or between several non-state actors on the territory of a state are governed by common Art. 3, by -for its state parties- AP II as well as by custom. Consequently, a state that is involved in a NIAC but is not a party to AP II is only bound by common Art. 3 together with customary rules and principles.


While international armed conflicts involve states as the sole actors, non-international armed conflicts include non-state actors such as organized armed groups fighting a state. The treatment of non-state actors under non-international armed conflicts does not grant them any legitimacy, their regulation aims to safeguard innocent civilians in armed conflicts.

D. Customary law and the core principles of the law of armed conflict Edit

Before the adoption of mentioned treaties, parties to a conflict have treated prisoners humanely, and exchanged prisoners of war in the aftermath of conflicts. These practices, as an effect of the consistent practice and opinio juris of belligerent states, gradually emerged as customary rules of the law of armed conflict.[7] These customs[8] were also codified in treaties, such as in the 1899/1907 Hague Regulations, the 1949 Geneva Conventions or in the 1977 Additional Protocols. One might ask that given the fact that customary rules find expressions in treaty laws, why do they need to continue having a separate existence as customary laws? Since a non-state party to a treaty could claim exemptions from treaty law, such a state is still bound by parallel customary rules.

The fundamental principles of the law of armed conflict, such as humanity, distinction, military necessity, proportionality as well as the obligation to take all feasible precautions enjoy the status of customary law,[9] and form the red thread of the law of armed conflict.[10] They apply to IACs and NIACs. Their objective is to generally "humanise" warfare without challenging the justifications for the initial aggression. They assist in maintaining the balance between military necessity and humanitarian protection.

I. Humanity Edit

Following the principle of humanity, states have adopted norms prohibiting cruel and inhuman treatments of opponents, especially regarding prisoners of war.[11] The scope of these laws has been expanded to include wounded, sick, shipwrecked, and non-combatants. In NIACs, the principle can be found today in common Art. 3, which prohibits the inhumane treatment of all those persons not participating in hostilities,[12] as well as for state parties to AP II in its Art. 4 stating that no circumstance in warfare can deprive a human of his/her right to be treated as human.[13] In IACs, Art. 75(1) AP I emphasises the humane treatment of individuals without discrimination.[14] Additionally, the principle of humanity enjoys customary status,[15] applicable to states and non-states alike.

II. Distinction Edit

Distinction determines who and what can be targeted in the conduct of hostilities (see e.g. Art. 48 AP I). It has emerged as a "cardinal" principle in treaty as well as in customary law.[16] It determines that civilians and civilian objects are never a lawful target in warfare, while military objects and combatants can generally lawfully be attacked. Nevertheless, under very limited conditions, and only if proportionate, there can be permissible collateral damage to civilians and civilian objects. It is important to read it together with other rules ensuring the protection of civilians. For instance, until and unless civilians participate in hostilities directly, they are legally protected from belligerent attacks.[17] Historically, most codes on violent conduct stressed, albeit in varying degrees, sparing humans and civilian objects not engaging in violence. The 1899/1907 Hague Regulations (Art. 25) does not specifically use the word "civilians", but outlaws 'the attack or bombardment, by whatever means, of towns, villages, dwellings, or buildings which are undefended'.[18] This has been interpreted as protecting civilians in conflicts, and relies on a distinction between those armed to take part in the fighting and those not participating in the hostilities. For IACs, Art. 57 (2)(b) AP I stresses that only direct armed attacks against combatants and military objects are lawful. In NIACs, Art. (13)2 AP II prohibits attacks on the civilian population, it also prohibits treating civilians and civilian objects as an object of attack. It is also outlawed to cause terror among the civilians by indiscriminate attacks.[19]Parallel in IACs, Art. 57(1) AP I stipulates that 'in the conduct of military operations, constant care shall be taken to spare the civilian population, civilians and civilian objects'. The latter, furthermore, laying out the point of the centrality of the safety of civilians, in its sub-Art. 57 (2)(a)(ii) stresses that all parties in a conflict should take utmost care ‘in the choice of means and methods of attack with a view to avoiding, and in any event to minimising, incidental loss of civilian life, injury to civilians and damage to civilian objects'.[20]

Additionally, weapons law and in particular Amended Protocol II to the Convention on Certain Conventional Weapons in its Art. 3(8)(a, b + c) also emphasise the principle of distinction by prohibiting indiscriminate usage of conventional weapons against the civilian populations and civilian inhabited dwellings.[21]

III. Military Necessity Edit

In IACs and NIACs, military necessity comes into play when translating the military objectives into military force deployment. According to the principle of military necessity, actions which are necessary to accomplish a legitimate military purpose and are not otherwise prohibited by international humanitarian law can be lawful. Usually, the only lawful military purpose is to weaken the military capacity of the other belligerent parties.[22] Concerning first attempt to codify laws of war, the American 1863 Lieber Code emphasises military necessity in war. Art. 4 of this Code explains that 'as understood by modern civilised nations, consists in the necessity of those measures which are indispensable for securing the ends of the war, and which are lawful according to the modern law and usages of war'.[23] In the 1899/1907 Hague Regulations, Art. 23(g) prohibits 'to destroy or seize the enemy's property, unless such destruction or seizure be imperatively demanded by the necessities of war'.[24] It is also noteworthy that while military necessity might be an outcome of military objectives, every violent act ought to have its own reasoning for qualifying as a permissible act in warfare. Such a reasoning should entail the requirements of another basic principle of warfare, namely the principle of proportionality.[25]

IV. Proportionality Edit

Proportionality is inter alia enshrined in Art. 51(5)(b) AP I which states that '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'.[26] It puts the damage caused by military activities into relation with the military advantage and requires that the effects of the means and methods of warfare cannot be disproportionate to the military advantage.[27] This principle plays a major role when determining the balance between military necessity and humanitarian protection in a case at hand. With regard to the interpretation of this principle, it is common understanding among states that 'direct military advantage' speaks of the operation as a whole advantage and shall not be assessed against every bit and part of the attack.[28]

Proportionality is extended to the various principles as explained above and applies in IACs and NIACs. It is important to remember that while military necessity speaks of the criteria to choose a military target, proportionality lays down the limits of a specific military action to neutralise such a target.

V. To Take all Feasible Precautions Edit

The principle of precaution was initially set out in Art. 2 of the 1907 Hague Convention (IX). It provides that given the presence of a military target inside an undefended town or port, it is important for the military commander to 'take all due measures in order that the town may suffer as little harm as possible'.[29] Subsequently, this principle was further specified in Art. 57 AP I for IACs,stating that it is incumbent upon the warring parties to 'do everything feasible to verify that the objectives to be attacked are neither civilians nor civilian objects and are not subject to special protection'.[30] Likewise, the 2nd Protocol to the Hague Convention for the Protection of Cultural Property also incorporates the element of precaution in conducting hostilities.[31]

Most states, in one way or another, have thrashed out the principle of precaution (as well as the other cardinal principles) in their military manuals to train their armed forces.

E. Actors in the law of armed conflict Edit

I. States Edit

States as traditional subjects of international law play an important role in the law of armed conflict like in any other field of public international law. For centuries, they have been an important actor in armed conflicts: They have started armed conflicts, they have participated in hostilities, they occupied territory and they came together to negotiate armistices. In collective efforts, states also assembled at international peace conferences, like the ones leading to the conclusion of the first Geneva Convention from 1863, the 1899/1907 Hague Regulations or the 1949 Geneva Conventions. The role of states is also illustrated in the two categories of armed conflicts that exist in the law of armed conflict (cf. common Art. 2 + 3 of the Geneva Conventions), namely IACs and NIACs.

II. Non-State Actors Edit

Over the past decades, many NIACs took place, with one state fighting an organised armed group or several ones within its territory, and vice versa. These situations are regulated by common Art. 3 to the Geneva Conventions and AP II, if the state concerned is a state party to AP II. This explains the rise of so-called non-state actors. Examples for such conflicts are, for instance, the one in Colombia with the FARC guerilla group fighting the government, or in the aftermath of 9/11 with Al-Qaeda fighting several states. Rebel and terrorist groups are thus belligrent parties in NIACs and lawfully participate in the hostilities as armed non-state actors under the law of armed conflict.

The law of armed conflict directly addresses them in common Art. 3 to the Geneva Conventions and in AP II.

Other non-state actors involved in armed conflicts include private military and security companies that support parties to a conflict.

Despite their active role in conflicts, non-state actors do not participate in the actual law-making procedure in the law of armed conflict. They are not a party to any treaties in the field, such treaties are concluded between states exclusively. In peace negotiations, on the other hand, non-state actors participate together with states. Their actions are also only indirectly considered when interpreting the law of armed conflict,[32] and when identifying rules and principles of customary law.[33] Compliance of armed non-state actors with the laws of armed conflict still represents a challenge in wartime.[34]

III. The International Committee of the Red Cross Edit

The International Committee of the Red Cross (ICRC) is the "guardian"[35] of the law of armed conflict. Established in 1863 as a Swiss association, the ICRC is mandated to protect people affected by armed conflicts. As a historical subject of international law, it enjoys a special international legal status that is different than the one from NGOs, who are not subjects of international law, or international organisations, who mostly enjoy a derivated subjectivity in international law. The ICRC is guided by seven principles: Humanity, impartiality, neutrality, independence, voluntary service, unity & universality,[36] which allow access to all parties to a conflict without any condemnation.

F. Selection of current challenges in the law of armed conflict Edit

The law of armed conflict as a field of law that was first codified in the mid-19th century is currently facing several challenges. Only a selection of some of these challenges can be addressed in this section.

I. Protected Groups and Objects Edit

The law of armed conflict was originally created by states to spare the civilians and the civilian population from the consequences of war. While the principle of distinction prohibits direct attacks against civilians generally, some provisions of the Geneva Conventions and their additional protocols address other specific groups or objects, such as medical personnel and establishments, cultural property, or the natural environment. Their protection is often linked to the protection of civilians and civilian objects, but these provisions install special protection for specific protected groups and objects that differs from the general protection of civilians and civilian objects. The three mentioned examples are only a selection of protected groups and objects, which are particularly valuable and hence often vulnerable in armed conflicts.

1. Medical Personnel Edit

The 1864 Geneva Convention was concluded to take care of the wounded and sick combatants of all belligerent states who were hors de combat (out of the battle). Without medical personnel and medical care, their protection would have remained meaningless. Hence, medical personnel is of particularly high value due to the essential role of medical care to each belligerent party. Today, several of the Geneva Conventions as well as AP I and AP II include provisions on the protection of medical personnel, medical units, and medical establishments. Art. 24 and 25 GC I, Art. 36 and 37 GC II, Art. 15 AP I on international armed conflicts, and Art. 9 AP II on non-international armed conflicts contain an obligation to respect and protect medical personnel under all circumstances: Medical personnel and medical establishments enjoy protection and cannot lawfully be made an object to an attack. In the battlefield, they enjoy protection when fulfilling their medical duties in conformity with medical ethics.[37] Attacking them intentionally is a war crime under Art. 8(2) lit. b(xxiv) and 8(2) lit. e(ii) Rome Statute. If medical personnel itself participates in the hostilities, they lose their protection.[38] Medical personnel includes civilians and militaries temporarily or permanently assigned to medical purposes, such as the search for, collection, transportation, diagnosis or treatment of the wounded, sick and shipwrecked, the prevention of diseases, or the administration or operation of medical units or medical transports.

If they fall into the enemy's hands, they are not considered prisoners of war and must be set free.[39] The opposing party may, however, retain them to give medical care to prisoners of war, but they cannot be asked to perform acts contrary to medical ethics.[40] Only people with the official assignment of medical tasks by the competent authority of a belligerent party enjoy the special protection as medical personnel. To identify medical personnel, it is asked to use the distinctive sign of the red cross, red crescent, or red crystal worn on clothes. In the past, the distinctive sign has made medical personnel and medical units more vulnerable in the field, since they were visible to the enemy's forces and have been attacked unlawfully, posing one main challenge in current warfare.[41]

2. Cultural Property Edit

Cultural property enjoys special protection in armed conflicts.[42] The two additional protocols contain provisions specifically protecting for cultural property in IAC and NIAC. Additionally, the Hague Convention for the protection of cultural property in the event of armed conflict from 1954 and its two protocols complement the protection based on the Geneva law.[43] The Preamble of the 1954 Hague Convention explains the rational behind the protection of cultural property in armed conflicts: "any damage to cultural property, irrespective of the people it belongs to, is a damage to the cultural heritage of all humanity, because every people contributes to the world's culture." Examples from the past, like in the Mali conflict when a series of intentional attacks by parties to the conflicts against mausoleums, mosques and historical monuments in the city of Timbuktu led to an international outcry, illustrate the meaning of cultural property and its importance to all. Destruction of cultural heritage can amount to a war crime under the Rome Statute.[44]

3. Natural Environment Edit

The environment has been called a "silent victim" of war.[45] Since the unlawful Russian aggression against Ukraine, not only NGOs but also media report regularly on wartime environmental damage. Only since the aftermath of the Vietnam War and with the adoption of AP I, the "natural environment" enjoys specific protection from "widespread, long-term and severe damage" in IACs (see. Art. 35(3) and 55(1) AP I). This cumulative threshold, however, has never been applied to an actual conflict for various reasons. First of all, not all states to the conflict were party to AP I, and it did consequently not apply.[46] Second, during the negotiations of AP I, no consensus among states was reached regarding the definitions of this very vague threshold. For instance, it is unclear whether "long-term" is measured in years or decades, based on the travaux préparatoires the latter seems to be the case.[47] Most scholars assume that is was not even reached in the cases of the Vietnam war and the deployment of Agent Orange, or when burning oil wells in Kuwait in 1991.

Parallel to the negotiation of AP I, states adopted the Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (ENMOD Convention), which contains a similar threshold with almost identical wording ("widespread, long-lasting or severe"). In this case, states were able to agree on definitions in a memorandum of understanding: long-lasting, for instance, means "lasting for a period of months, or approximately a season" in terms of the ENMOD Convention.[48]

In addition to the specific protection the "natural" environment enjoys under Art. 35(3) AP I, elements of the environment can constitute civilian objects.[49] They rarely serve military purposes and hence only rarely represent a military object that can lawfully be attacked. Consequently, the principle of distinction protects the parts of the environment in general. The other cardinal principles of the law of armed conflict, like proportionality, military necessity, and precautions in an attack, also require the belligerent parties to at least consider the protection of the environment in their conduct of hostilities.[50]

In NIACs, which are regulated by common Art. 3 and AP II, there exists no specific provision on the environment. Consequently, the environment enjoys protection as a civilian object and according to the cardinal principles.

As regards custom, the 2005 ICRC study on customary international humanitarian law identified three rules on the natural environment.[51] Their legal nature, however, is disputed and represents in parts at least progressive development of the law. Additionally, the UN International Law Commission has adopted 27 principles on the topic "Protection of the Environment in relation to Armed Conflicts" with the aim of enhancing the protection of the environment by combining the law of armed conflict with human rights law and international environmental law obligations.[52] They address the environment before, during, and after an armed conflict and represent codification as well as progressive development of international norms. They also include suggestions on how to improve environmental protection in an armed conflict.

In sum, the natural environmental enjoys protection in armed conflict, even though the exact obligations are far from being clear. Most importantly, the protection of the environment as a civilian object and based on other provisions indirectly protecting it, such as Art. 56 AP I on installations containing dangerous forces such as nuclear power plants or dams.

II. New Technologies Edit

Beyond the frontiers of laying down elaborative and consensual rules to avoid human suffering in wars, there lies the challenge of inventing and deploying weapons which might not impede the human capacity and willingness to abide by these rules. In present times, with the invention and introduction of various new technologies of warfare such a challenge has become more pronounced than ever.

1. Semi-Autonomous Weapons Edit

Warfare technologies have made unprecedented strides in the last few decades: the leap from manned military technology to the unmanned was rapid and reciprocal. Such a swiftness in development and deployment provides a strategic and operational edge, it also raises numerous legal questions concerning the principles of warfare like distinction, necessity, proportionality, etc. Undoubtedly, semi-autonomous weapons like combat drones are more precise and proportionate, at least in theory. Combat drones were presented as the "weapon of choice" at the start of the "war on terror".[53] While the results on saving the lives of drone operators are certainly positive, the losses of lives when targeting the alleged terrorists are in many cases not proportionate to the actual security threat they pose. For instance, in case of the US drone attacks against terrorists in Pakistan, Yemen, and Somalia, various governmental and non-governmental studies point to the fact that in contrast to their technological reputation for precision, combat drones are not that much precise, operationally.[54] Nonetheless, the US remains adamant that the combat drones are precise and avoid losses to the innocent lives. In view of the discrepancies surrounding the loss of innocent civilian lives, one may notice that the dispute over evidence while on the one hand seems to be inherent when it comes to the application of laws in war. On the other, it points to the fact of the mere confidence of the governments in the precision of combat drones.

However, at times, such confidence did translate into reality of precision strikes, as combat drones pinpointed the terrorists on various occasions. For instance, the killing of a Pakistani Taliban leader in a drone strike, wherein the missile attack was so precise that even it did not cause any harm to the house, bore testimony to this fact.[55] In this case, it seems that the drone operators took 'all feasible precautions' before striking down the intended target, and adequately fulfilled the principles of necessity and proportionality. Hence, concerning the technological prowess of combat drones, it is evident that they have the manifest ability to be precise and proportional. Unlike soldiers on the battlefield, combat drones do not fear for their safety, and hence, in principle can withstand risks while pinpointing the target. In practice, however, the usage of combat drones, specifically against the belligerent non-state actors, in recent times, raised more questions, concerning the fulfilment of humanitarian principles than answering them. In this context, one needs to closely study the combat drone deployments in Pakistan, Yemen, and various African states involving the United States and French militaries against terrorists.[56]

2. AI and Autonomous Weapons Edit

Within the context of the weapons of warfare, autonomy is a relative term. It may range as well as encompass launching a weapon into the battlefield to the point of successfully selecting, engaging, and neutralising the target.[57] To make the concept more understandable, the United States Department of Defense underlines that a weapons system is autonomous when 'once activated, (it) can select and engage targets without further intervention by a human operator'.[58] In the case of semi-autonomous weapons when humans remain in the loop by deciding and targeting the enemy combatants on the battlefield, humans deem to be handing over control over crucial decisions to machines. In fact, humans might decide instantly that a certain objective of warfare can be better served by only injuring the enemy combatant rather than killing him/her. An automated weapon would hardly bother to take such decision and spare the life of a human in return for only injuring him/her. Likewise, speaking of strategic and nuclear weapons, the mere presence of autonomous weapons can be tempting for the adversary to jump to the conclusion that these weapons might be used in a first strike scenario, and therefore, it might appear prudent to unleash the strategic weapons in advance. Such a scenario makes escalation scenarios in warfare more uncertain and dangerous. It undermines the principle of proportionality.[59]

Moreover, autonomous weapons have serious repercussions for the principle of distinction. For instance, though an automated gun is fed with various image classifications such as soldier uniforms, insignias, numerous types of rifles and ammunitions yet the softwares commanding the operations of a gun can be hacked and fed with different image classification. For example, in certain experiments guns have mistaken turtles as rifles.[60] Despite some voices raising serious ethical, legal, and political questions[61] about the nature as well as about certain characteristics of autonomous weapons challenging the cardinal principles, some scholars note that automated killing machines may be better suited to comb through the security threats, and thus, without fearing for its own safety, target the militarily vital object or combatant.[62]

In this context, one might presume that innovation in weapons is driven by the understanding that it might spare the lives of those seeking an edge in technology, yet it is also important to understand that these innovations must not make laws in warfare ineffective. Beginning with St. Petersburg Declaration and the Hague Declarations and Regulations, only those weapons should be deployed in warfare which ensure the avoidance of unnecessary injury. Similarly the Geneva Conventions and AP I in Art. 51 and 57 stress the importance of avoiding excessive physical and material damages in warfare. Avoidance of excessive damage in terms of the autonomous weapons depends upon the efficient decision-making. Autonomous weapons based on data feeds, however, reach decisions within moments, and thus, might undermine the role of human judgement.[63] Already we know that with regard to the semi-autonomous weapons, interplay between human judgement and machines have often produced horrible consequences when it comes to upholding the humanitarian principles in warfare. Autonomous weapons, therefore, do not seem to be offering any better alternatives to humans when taking decisions of applying kinetic force. The fulfilment of humanitarian principles, certainly, demands more role for the human judgement, not less.

3. Cyber Weapons Edit

In present times, while a networked world generates an unprecedented level of prosperity, it also poses an extraordinary challenge to secure the very platforms underpinning this networking. In such networks, signals across and within the digital platforms remain the critical mass. An ill-intended intrusion or tempering with the signals can turn a benevolent digital tool into a destructive weapon. And the resultant destruction can be equal to an armed attack, triggering the right to self-defence under Art. 51 UN Charter. In this context, spy wares and malicious software codes have already brought down the governmental digital platforms in Estonia and destroyed certain nuclear reactors in Iran. Scenarios like shutting down the electricity grids or bringing down a commercial airplane by introducing malware in their control and navigation systems are also being drawn.

In the conduct of hostilities (and not regarding the jus ad bellum which has to be analysed separately), these scenarios render the conduct of violence an utterly discreet activity: wherein the questions of distinction and proportionality will once more come to the fore. Even to begin with, there are questions about determining damages caused by cyber weapons as an 'attack' as well as fixing the responsibility for such acts. Responding to such concerns, the ICRC notes that only state practice can help finding adequate answers.[64] For instance, no one claimed responsibility for damaging Iranian and Estonian infrastructures. Also, when hitting the targets, there was no regard for the principle of distinction either. Specifically speaking of the principle of distinction in Art. 48 AP I becomes problematic with regard to the cyber warfare. For example, due to the easiness and less costly prospects, a military commander decides to shut down an electricity grid by a cyber attack to disrupt the command and communication structures of a nearby military installation, yet the same targeting can also turn off electricity in a nearby hospital and cause scores of deaths. The loss of innocent lives becomes an unintended consequence of a cyber attack. Besides violating the principle of distinction, such an attack also ends up undermining the principles of humanity, military necessity as well as proportionality.[65]

To address these issues in cyber warfare, some scholars suggest to introduce binding international conventions protecting civilian digital platforms.[66] Nonetheless, questions shall arise when targeting those platforms powering civilian and military installations simultaneously, because the targeting entity will not be able to distinguish between civilian and military installation, as the digital platform will be plugged into both installations. Speaking of the functioning of cyber platforms, one can assume that such a dilemma will not be specific to the given case rather it will run across numerous platforms, thus, complicating any military targeting decisions.[67] Hence when a targeting decision is taken and executed, in all probability, it will give rise to questions about the applicability of proportionality. After all, pinpointing a networked target is extremely difficult and chances of indirectly targeting civilian cyber infrastructure are higher during a conflict.[68] Massive cyber attacks against the Ukrainian government's digital infrastructure once more point toward such trends and difficulties when targeting cyber objects.[69] Tracing the sources to fix responsibility for usages and damages caused by cyber weapons is another dilemma, potentially, making the violence in war a muddier business and adding another layer of complexity in applying the legal principles to ensure transparency as well as accountability.[70] Apparently unlike autonomous and semi-autonomous weapons, cyber weapons due to their nature, are more prone to be indiscriminate and disproportionate (as evidence by the example of grid station above). To make their use subject to the given humanitarian rules and principles is bound to pose serious challenges.

G. Interplay with Other Fields of Public International Law Edit

Decades ago, the law of war represented the lex specialis in war-related matters.[71] With the adoption of the 1949 Geneva Conventions and the "humanisation" of the law of war since the post-WW II period, there is agreement today among states and scholars that human rights can complement the law of war under certain conditions, particularly based on non-derogable human rights such as the right to life. Kolb described the relationship of international humanitarian law and human rights as follows: "In 1945, IHL and HRL were as distant as Scylla and Charybdis; today they are as inseparable as Castor and Pollux."[72] Regional and universal human rights systems as well as the International Court of Justice have clarified questions at the intersection of human rights law and the law of war in the past decade.[73] In 1996, the International Court of Justice in the advisory opinion on the Legality of the Threat or Use of Nuclear Weapons stated that

[. . .] the protection of the International Covenant of Civil and Political Rights does not cease in times of war, except by operation of Article 4 of the Covenant whereby certain provisions may be derogated from in a time of national emergency. Respect for the right to life is not, however, such a provision. In principle, the right not arbitrarily to be deprived of one’s life applies also in hostilities. The test of what is an arbitrary deprivation of life, however, then falls to be determined by the applicable lex specialis, namely, the law applicable in armed conflict which is designed to regulate the conduct of hostilities."[74] In 2005, it specified the interplay in the Wall Advisory Opinion by stating that "[a]s regards the relationship between international humanitarian law and human rights law, there are thus three possible situations: some rights may be exclusively matters of international humanitarian law; others may be exclusively matters of human rights law; yet others may be matters of both these branches of international law."[75]

These options of an interplay have been further elaborated on in scholarship,[76] but in the end it is a case-by-case analysis on whether and how the law of war is complemented by human rights.

In addition to certain human rights, other fields also co-exist or apply simultaneously to the law of war. The UN International Law Commission in its work on "The Effects of Armed Conflict on Treaties"[77] in 2011 stated in draft Article 7 that there exists an implication that certain treaties continue to "in operation" during an armed conflict. The Commission annexed a list of treaties that presumingly continue to apply during armed conflict to the draft principles, these include treaties like international environmental law, treaties of friendship, commerce and navigation and agreements concerning private rights, or treaties declaring, creating or regulating a permanent regime or status or related permanent rights, including treaties establishing or modifying land and maritime boundaries. Consequently, international environmental law and in particular so-called multilateral environmental treaties are not ipso iure suspended in case of an armed conflict.[78] The World Heritage Convention or the Biodiversity Convention are treaties that are studied today in terms of their continued application in war zones.[79] Is has to be determined on a case-by-case study whether and how other fields of public international law complement the law of war.

International criminal law is another field of public international law that complements the law of war, but in a very special way. In the Rome Statute, states have codified and criminalised war crimes, which are conducted during hostilities, thus relating to the law of war. The Office of the Prosecutor of the International Criminal Court, however, only investigates crimes as agreed upon in the Rome Statute, thus separating the law of war from international criminal law and resulting in differing legal standards.

Further Readings Edit

Further Resources Edit

Summary Edit

  • This chapter sums up the primary norms, rules, actors, and subjects of the law of armed conflict.
  • Also, it extrapolates the ways in which the modern tools of warfare like semi-autonomous and autonomous weapons, cyber weapons, potentially, challenge the existent rules governing the conduct of hostilities in armed conflicts. Moreover, it explains how specific protected groups and object are protected in war.

Table of Contents Edit

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Part I - History, Theory, and Methods

Part II - General International Law

Part III - Specialized Fields

Footnotes Edit

  1. Marco Sassòli, Antoine Bouvier and Anne Quintin, How Does Law Protect in War? Cases, Documents and Teaching Materials on Contemporary Practice in International Humanitarian Law (Vol. I, 3rd ed, ICRC Publications 2011) 1.
  2. Dunant, A Memory of Solferino, available at
  3. Fought between the French troops, allied to the Sardinians, and the Austrians troops on June 24, 1859, the battle of Solferino left 6,000 dead and 40,000 wounded on the very first day. The sufferings of unattended wounded as observed by Henry Dunant gave way to the formation of the Red Cross. For details, 'The battle of Solferino' (1859) <> accessed 23 June 2022
  4. Janne Elisabeth Nijman, "Bertha von Suttner: Locating International Law in Novel and Salon," in: Immi Tallgren, Portraits of Women in International Law - New Names and Forgotten Faces?, OUP 2022.
  5. Frits Kalshoven and Liesbeth Zegveld, Constraints on the Waging of War: An Introduction to International Humanitarian Law (ICRC Publications 2001) 27-29.
  6. See ICRC, Commentary GC I, pp 81–82 para. 224, available at; D. Akande, Classification of Armed Conflicts: Relevant Legal Concepts, in: E. Wilmshurst (ed.), International Law and the Classification of Conflicts (OUP, 2012), pp 32–79; J. K. Kleffner, Scope of Application of International Humanitarian Law, in: Fleck (ed.), Handbook of International Humanitarian Law, 4th ed., 2021, p. 52, para. 3
  7. Kalshoven and Zegveld (n 7) 15.
  8. The ICRC has conducted a study on customary IHL in 2005 and since then regularly updates the analysis of state practice and opinio juris. It is available online at
  9. ICRC. "Fundamental principles of IHL". Retrieved 26 June 2022.
  10. Cf. Dinstein (2016), Conduct of hostilities, §§34+35.
  11. 'Lieber Code: Instructions for the Government of Armies of the United States in the Field' (24 April 1863) <> accessed 24 June 2022
  12. 'Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field' (12 August 1949) <> accessed 25 June 2022
  13. 'Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of Non-International Armed Conflicts (Protocol II)' (8 June 1977) <> accessed 26 June 2022
  14. 'Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) (8 June 1977) <> accessed 26 June 2022
  15. For a detailed treatment of this principle as a customary norm, Jean-Marie Henckaerts and Louise Doswald-Beck, Customary International Humanitarian Law (Vol. I, CUP 2005) 306-343.
  16. Legality of the Threat or Use of Nuclear Weapons (n 10) para 78, 92.
  17. Henckaerts and Doswald-Beck (n 16) 3.
  18. 'Convention (IV) respecting the Laws and Customs of War on Land and its annex: Regulations concerning the Laws and Customs of War on Land' (18 October 1907) The Hague <> accessed 26 June 2022
  19. 'Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of Non-International Armed Conflicts (Protocol II)' (8 June 1977) <> accessed 25 June 2022
  20. 'Protocol Additional to the Geneva Conventions' (n 21).
  21. 'Protocol on Prohibitions or Restrictions on the Use of Mines, Booby-Traps and Other Devices as amended on 3 May 1996 (Protocol II to the 1980 CCW Convention as amended on 3 May 1996) <> accessed 27 June 2022
  22. ICRC. "Military necessity". Retrieved 26 June 2022.
  23. 'Lieber Code' (n 12).
  24. 'Convention (IV) respecting the Laws and Customs of War on Land and its annex: Regulations concerning the Laws and Customs of War on Land' (18 October 1907) The Hague <> accessed 27 June 2022
  25. Oscar Schachter and Frits Kalshoven, Proceedings of the Annual Meeting (1992) 86 ASIL 41.
  26. 'Protocol Additional to the Geneva Conventions' (n 21).
  27. ICRC. "Proportionality". Retrieved 26 June 2022.
  28. Henckaerts and Doswald-Beck (n 16) 49-51.
  29. 'Convention (IX) concerning Bombardment by Naval Forces in Time of War' (18 October 1907) The Hague <> accessed 28 June 2022
  30. 'Protocol Additional to the Geneva Conventions' (n 21) art (57)(2)(a)(i) <> accessed 28 June 2022
  31. 'Second Protocol to the Hague Convention of 1954 for the Protection of Cultural Property in the Event of Armed Conflict' (26 March 1999) The Hague art 7 <> accessed 28 June 2022
  32. Cf. conclusion 7 and its commentary of the ILC's draft conclusions on subsequent agreements and subsequent practice in relation to the interpretation of treaties with commentaries, available at
  33. Cf. conclusion 4, para 4 of the ILC's draft conclusions on the identification of customary international law with commentaries, available at
  34. Bellal/Casey-Maslen, Enhancing Compliance with International Law by Armed Non-State Actors, Goettingen J. Int'l L. 2011, pp 175-197; see e.g. the initiative Geneva Call who aims at enhancing compliance of armed non-state actors in their conduct of hostilities to improve the protection of civilians:
  35. ICRC blog, What is the ICRC's role in developing and ensuring respect for IHL?, available at
  36. See ICRC, Research guide "The Fundamental Principles of the International Red Cross and Red Crescent Movement," available at
  37. See Articles 24+25 GC I, Articles 36+37 GC II, Articles 15+16 AP I.
  38. See e.g.,the%20International%20Criminal%20Court%20(Arts.
  39. See e.g. Articles 28-32 GC I.
  40. See e.g. Articles 15+16 AP I and Art. 10 AP II.
  41. See e.g. Haar, Rohini J., et al., "Violence against healthcare in conflict: a systematic review of the literature and agenda for future research," Conflict and health 15.1 (2021), 1-18.
  42. See generally, O'Keefe, Roger, The protection of cultural property in armed conflict, CUP 2006.
  43. Art. 53 AP I and Art. 16 AP II. Cultural property also enjoys protection under customary law, see - Chapter 12 ICRC IHL study, available at
  44. See e.g. the Al Mahdi Case by the ICC, The Prosecutor v. Ahmad Al Faqi Al Mahdi, ICC-01/12-01/15, more information available at
  45. UN Environment Programme, Rooting for the Environment in Times of Conflict and War, Press release from 6 November 2019, available at (last visited 15 March 2022)
  46. See Dörmann/Colassis, International humanitarian law in the Iraq conflict, German YB Int'l L. (2004) 47, pp. 294ff.
  47. Dienelt, Armed Conflicts and the Environment: Complementing the Laws of Armed Conflict with Human Rights Law and International Environmental Law, Springer 2022, pp 57 ff.
  48. See (last visited 15 March 2022)
  49. See Droege/Tougas, The Protection of the Natural Environment in Armed Conflict–Existing Rules and need for further legal protection, Nordic Journal of International Law 2013, p. 23
  50. See ICJ, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion from 8 July 1996, ICJ Rep. 1996, para. 30: "[…] States must take environmental considerations into account when assessing what is necessary and proportionate in the pursuit of legitimate military objectives. Respect for the environment is one of the elements that go to assessing whether an action is in conformity with the principles of necessity and proportionality.”
  51. Cf. rules 43-45 in chapter 14, available at (last visited 15 March 2022)
  52. See e.g. Sjöstedt, The role of multilateral environmental agreements: A reconciliatory approach to environmental protection in armed conflict, Bloomsbury Publishing 2020, or Dienelt, Armed Conflicts and the Environment: Complementing the Laws of Armed Conflict with Human Rights Law and International Environmental Law, Springer 2022, pp 234 ff.
  53. Remarks of Director of Central Intelligence Agency, Leon E. Panetta, at the Pacific Council on International Policy (May 18, 2009) <> accessed 23 July 2022
  54. 'Living under Drones: Death, Injury and Trauma to Civilians from US Drone Practice in Pakistan (International Human Rights and Conflict Resolution Clinic, Stanford Law School and Global Justice Clinic, New York University School of Law 2012); Jo Becker and Scott Shane, 'Secret "Kill List" Proves a Test of Obama’s Principles and Will,' The New York Times (29 May 2012) A1; Letta Tayler, 'Between a Drone and Al-Qaeda: The Civilian Cost of US Targeted Killing in Yemen,' (New York, Human Rights Watch 2013); Jane Mayer, 'The Predator War: What are the Risks of the C.I.A.’s Covert Drone Program?' The New Yorker (26 October 2009); 'Daily Situation Report,' (FATA Secretariat, Ministry of Interior, Pakistan, 2007-2017; Ben Emmerson, 'Report of the Special Rapporteur on the Promotion and Protection of Human Rights and Fundamental Freedoms While Countering Terrorism,' UN Document A/68/389 (18 September 2013); Philip Alston, 'Report of the Special Rapporteur on extrajudicial, summary or arbitrary executions,' (presented to the Human Rights Council, 14th session, 28 May 2010).
  55. Imdad Ullah, Terrorism and the US Drone Attacks in Pakistan: Killing First (Routledge 2021) 131.
  56. Hugh Gusterson, Drone: Remote Control Warfare (The MIT Press 2016); 'Civilian Casualties & Collateral Damage,' (n 46); Letta Tayler, 'Between a Drone and Al-Qaeda: The Civilian Cost of US Targeted Killing in Yemen,' (Human Rights Watch 2013) <> accessed 23 July 2022; 'A Wedding That Became a Funeral,' (Human Rights Watch 2014); 'France's Shadow War in Mali: Airstrikes at the Bounti Wedding,' (Stoke White Investigations 2021) <> accessed 24 July 2022
  57. For a detailed treatment of autonomy in autonomous weapons systems and how may it operate in warfare, see Kenneth Payne, 'Artificial Intelligence: Artificial Intelligence: A Revolution in Strategic Affairs?' (2018) 60 Survival 7-32; Giovanni Sartor and Andrea Omicini, 'The autonomy of technological systems and responsibilities for their use' in Nehal Bhutta and others (eds), Autonomous Weapons Systems: Law, Ethics, Policy (CUP 2016) 40-65.
  58. 'Autonomy in Weapons Systems' U.S. Department of Defense, directive no. 3000.09 (21 November 2012)
  59. Michael T. Klare, 'Autonomous Weapons Systems and the Laws of War' (2019) 49 Arms Control Today 6-12.
  60. ibid.
  61. For details of such voices, Mary E. O’Connell, 'Banning Autonomous Killing—The Legal and Ethical Requirement That Humans Make Near- Time Lethal Decisions' in Matthew Evangelista and Henry Shue (eds), The American Way of Bombing: Changing Ethical and Legal Norms From Flying Fortresses to Drones (Cornell University Press 2014) 224-235; Rebecca Crootof, 'A Meaningful Floor For "Meaningful Human Control" (2016) 30 Temple International and Comparative Law Journal 53–62; Peter Asaro, 'Jus nascendi, Robotic Weapons and the Martens Clause' in Ryan Calo, Michael Froomkin and Ian Kerr (eds), Robot Law (Edward Elgar Publishing 2016) 367–386.
  62. Duncan Macintosh, 'Fire and Forget: A Moral Defense of the Use of Autonomous Weapons Systems in War and Peace' in Duncan Macintosh and Jens D. Ohlin (eds), Lethal Autonomous Weapons: Re- Examining the Law and Ethics of Robotic Warfare (OUP 2021) 9-23.
  63. Dan Saxon, 'A Human Touch: Autonomous Weapons, Directive 3000.09, and the "Appropriate Levels of Human Judgment over the Use of Force" (Summer/Fall 2014) 15/2 Georgetown Journal of International Affairs 103. For further details, see Bill Boothby, 'How Far Will the Law Allow Unmanned Targeting to Go?' in Dan Saxon (ed), International Humanitarian Law and the Changing Technology of War (Mārtiņus Nijhoff/Brill 2013) 62-63; and David Akerson, 'The Illegality of Offensive Lethal Autonomy' in Dan Saxon (ed), International Humanitarian Law and the Changing Technology of War (Mārtiņus Nijhoff/Brill 2013) 7I.
  64. 'International Humanitarian Law and the Challenges of Contemporary Armed Conflicts' (October 2015) ICRC, 16.
  65. Michael N. Schmitt, Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations (CUP 2017) 348-50.
  66. Davis Brown, 'A Proposal for an International Convention To Regulate the Use of Information Systems in Armed Conflict' (2006) 47/149 Harvard ILJ.
  67. For a detailed analysis of this targeting dilemma, see Michael N. Schmitt, 'The Law of Cyber Targeting' (Spring 2015) 68/2 Naval War College Review 10-29; Michael N. Schmitt and Eric W. Widmar, 'On Target: Precision and Balance in the Contemporary Law of Targeting' (2014) 7 Journal of National Security Law & Policy 379-409.
  68. ibid 26.
  69. Robert Hart, 'Ukraine Hit By "Massive Cyber Attack" As Russia Mobilizes Troops Near Border' (14 January 2022) Forbes <> accessed 30 July 2022
  70. For further details, Schmitt (n 59) 79-104.
  71. See e.g. Chapter 14 in: Fleck (ed.), The Handbook of International Humanitarian Law, 4th ed, CUP 2021.
  72. Kolb, "Human Rights and Humanitarian Law," para. 26, in: Peters A (ed), Max Planck Encyclopedia of Public International Law, OUP 2021.
  73. See e.g. IACommHR, Coard et Al. v. United States; IACommHR, Victor Saldaño v. Argentina; Report of the Special Rapporteur on the Situation of Human Rights in Occupied Kuwait, 50–54, UN Doc. E/CN.4/1992/26 from 16 January 1992.
  74. ICJ, Advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, §25.
  75. ICJ, Advisory opinion on the Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, §106.
  76. See e.g. Prud'homme, "Lex specialis: oversimplifying a more complex and multifaceted relationship?," Israel Law Review 40.2 (2007), pp 356-395; or Milanovic, "The lost origins of lex specialis – rethinking the relationship between human rights and international humanitarian law," in: Ohlin JD (ed), Theoretical boundaries of armed conflict and human rights, CUP 2016, pp 78–117.
  77. ILC, Draft articles on the effects of armed conflicts on treaties with commentaries, 2011, UN Doc. A/66/10.
  78. On multilateral environmental treaties and armed conflict, see. e.g. Sjöstedt,"The role of multilateral environmental agreements in armed conflict: ‘Green-keeping’in Virunga Park. Applying the UNESCO World Heritage Convention in the armed conflict of the Democratic Republic of the Congo," Nordic Journal of International Law 82.1 (2013), pp 129-153.
  79. See e.g. Dienelt, Armed Conflicts and the Environment: Complementing the Laws of Armed Conflict with Human Rights Law and International Environmental Law, Springer 2022, pp 234 ff.