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The Importance of International Humanitarian Law (IHL)

The Importance of IHL

As we write this, the eyes of the world are on the conflict in the Mideast. In response to the 7 October Hamas raid into southern Israel that killed around 1300 people, the majority of them civilians who were deliberately targeted, Israel is conducting preparatory bombardment of Gaza ahead of a likely ground invasion; over 2200 people in Gaza have reportedly been killed by airstrikes, a quarter of them children. Civilians in Gaza have been ordered by the Israeli government to flee south, and with Iranian support to Hamas and Hezbollah, the possibility exists for the conflict to erupt into a wider regional war. 

First and foremost, we at C2SI condemn, in the strongest terms, any harm to civilians by the belligerent parties, regardless of intent, and we extend our deepest sympathies to civilian victims, especially children, of this latest round of violence, and to the families of the slain; and we urge all parties to the conflict to de-escalate and seek peace with justice. Most of all, we urge combatants to comply with international humanitarian law (IHL), also known as jus in bello, the “law of war” or “law of armed conflict” (LOAC).

IHL is the body of treaty-based and customary international law governing the conduct of belligerents during hostilities, which seeks to limit the effects of armed conflict for humanitarian reasons. Compliance with IHL is a legal, moral, and practical necessity for any armed force, state or non-state, and for any individual who takes up arms in conflict; familiarity with IHL is thus an essential component of training for any combatant or potential combatant, whether in a conventional clash between armies as in Ukraine, or a war amongst the people as is looming in the Mideast. However, although most soldiers in democratic countries will probably have received some training on the basics of IHL, it is surprisingly poorly understood even among those involved in conflict – whether warfighters, first responders, aid workers, policymakers, or commentators, to say nothing of the general public.   

IHL is a complex and nuanced, and to some extent, contested body of law that can be challenging to parse. Luckily, there are a number of organizations providing resources and training to those with a practical need to understand and comply with IHL, such as Geneva Call and the ICRC (and it’s important here to emphasize that C2SI are not lawyers or experts on this topic – this blog post should not be understood as legal advice). However, training environments – especially time-constrained ones – may not present the opportunity to provide in-depth training on the topic. So what are the most important basic concepts for trainers and trainees alike – and indeed for anyone dealing with armed conflict – to understand? A full list would be a book, not a blog post, but here we’ll highlight some of the most important concepts. 

What is IHL? As noted above, IHL is the body of law that governs conduct in war to limit its effects. Here, we must emphasize the distinction between jus ad bellum – “just war doctrine” – and jus in bello, or IHL. The former is the set of treaty and customary law that governs the political decision for a state to go to war; simply, is there a just cause or not? IHL, by contrast, governs the conduct of combatants in war. We won’t dwell much on jus ad bellum, aside from saying that while prior to World War II, war was seen as a “right” of states, the UN Charter – the foundational treaty of the postwar rules-based international order – authorizes states to use force in only two circumstances: self-defense against an armed attack, and when authorized by the UN Security Council. 

The key takeaway here is this: the two bodies of law are completely separate and don’t impinge on one another. No matter whether your opponent has a just cause or not, you still need to comply with IHL, full stop. In other words, even if you’re fighting a reprehensible enemy like the Nazis, Islamic State, or the Russian armed forces and Wagner, you still have to comply with IHL in how you combat them. 

It’s also important to distinguish IHL from International Human Rights Law (IHRL); the former governs conduct in war and applies only during hostilities, while the latter governs how states treat individuals under their power and applies at all times (some jurists might contest this assertion and claim that the two bodies of law are exclusive). 

When does IHL apply? Quite simply, IHL applies in armed conflict. There are two types of armed conflict: international armed conflict (IAC), in which the armed forces of two or more states are directly fighting each other; and non-international armed conflict (NIAC), in which states are not directly fighting each other, but rather fighting non-state actors. A good example of the distinction is Syria; it has generally been a non-international armed conflict, as the fighting has been generally between states and non-state actors: the government against the rebels, the Turks against the People’s Protection Groups (YPG), the rebels against the YPG, and everyone against IS. However, it has from time to time escalated into an international armed conflict: for instance, in early 2020, Syrian government forces attacked Turkish Army positions, and the Turks responded with the systematic destruction of large numbers of Syrian government forces. Since World War II, and especially in the post-Cold War era, most wars have been non-international armed conflicts, reflecting the general prohibition on the use of force under the UN Charter and the rules-based international order; however, the frequency and scale of international armed conflicts – which are much more severe and destabilizing, given the greater power of states when compared to non-state actors – has been increasing, with the paradigmatic example being the Russian invasion of Ukraine.  

There are no strict criteria for when a state of armed conflict exists, but in most cases, like art, “you know it when you see it.”  

What are the core principles of IHL? While there is no set list based in treaty law, IHL is generally agreed to be rooted in several key principles, which are generally some variation of the following: distinction, prohibition on attacking those hors d’combat, proportionality, necessity, humanity, and precaution. 

In our words, the principle of distinction is that belligerents must distinguish between legitimate military targets (e.g., enemy combatants and military infrastructure) and prohibited ones (e.g., civilians and civilian infrastructure, protected personnel, and property). In other words, it’s illegal to shoot civilians (unless they engage in combat) or blow up houses, hospitals, and schools (except in cases of strict military necessity). 

The prohibition on harming those hors d’combat is a related concept: combatants may not harm enemy forces who have surrendered, or who have been rendered incapable of fighting by sickness, wounds, or other means. Shooting a man with his hands up is definitely a war crime; dropping a grenade from a drone on a wounded man probably is. 

The principle of proportionality is a related concept: the level of force used against a target must weigh potential military advantage against potential collateral damage. It’s a common misconception that proportionality governs the use of weapons against an individual target; if an enemy combatant is in an open field, it’s completely legal to engage him with anything from a rifle to a JDAM. Proportionality is about accounting for collateral damage. If that enemy combatant is a lone private in a densely populated area, dropping a JDAM is probably disproportionate and thus illegal, because the likelihood of killing innocent civilians or destroying their property is too high to justify such a means of engagement. However, that calculation may change if, for instance, the target is an enemy division-level headquarters in a populated area – from a legal perspective, the potential military advantage to be gained by destroying that target may outweigh the risk of collateral damage. 

This connects to the concept of military necessity. IHL rests on the assumption that, given a state of war exists, military force is being used to achieve objectives; however, the principle of necessity holds that such force should only be used in the service of legitimate military objectives, should be the minimum needed to achieve those objectives, and should be governed by the principles of distinction, proportionality, and humanity.

The principle of humanity – arguably the most important, fundamental principle of IHL – is simply that even in war, all possible measures should be taken to minimize suffering – of all people affected, especially civilians, and even the enemy – and avoid “unnecessary” suffering entirely (indeed, the “prohibition on unnecessary suffering” is often given as a principle of IHL, here rolled under the broader “humanity”). Means and methods of warfare that are especially cruel should not be used; for instance, restrictions on expanding bullets and incendiaries are driven by a commitment to the principle of humanity. Additionally, even in situations where the use of lethal force may be otherwise legitimate under IHL, the principle of humanity demands a combatant seek to limit it whenever possible, even at risk to its own forces. For instance, during an assault on a trench or a raid on a terrorist safehouse, the attacking force may slow its attack or limit its kinetic action in favor of “call-outs” to give the enemy more chances to surrender, thus seeking to preserve human life. For fighters raised on the concept of “violence of action,” this may go against their inclinations, but restraining violence in the name of humanity even in war is in the long-term interest of all humans.

A final principle to note is the principle of precaution; constant care must be taken to minimize the loss of civilian life. Measures such as leafleting to warn of military operations, ensuring safe routes and safe areas, restrictions on fires in populated areas, and accounting for the protection of civilian infrastructure and the means of survival during military operations all fall under the principle of precaution.         


What’s the basis of IHL? IHL, like all international law, derives from two sources: treaty law and customary law. The treaty law basis of IHL is on accords such as the Hague and Geneva Conventions, and various more recent conventions such as the Chemical Weapons (CW) Convention, the Convention on Certain Conventional Weapons (CCW), and the Mine Ban Treaty (Ottawa Treaty). Treaty law is based on the voluntary ratification of states party to the treaty and is straightforward: if a state ratifies or accedes to a treaty, it is bound to conduct itself according to that treaty. However, customary law is more contested. It is based on jurists’ interpretation of state practice. For instance, even if direct targeting of civilians and execution of prisoners weren’t banned by treaty law (which they are), they would almost certainly be considered to be banned customarily, as protection of prisoners and civilians has been a de facto normative practice of “civilized” war since at least the 19th century. 

However, IHL enters disputed territory especially around the use of certain “means and methods” of warfare, especially certain weapons. The key point here is this: simply because a treaty “banning” something exists, doesn’t mean it’s banned under normative law. For instance, while the Convention on Cluster Munitions (CCM) seeks to ban the use of such weapons, and a majority of the world’s states have ratified it, a large minority have not; thus it is unlikely that a jurist would assert that a prohibition on the use of cluster munitions has achieved the status of normative international law. However, the obverse is also true: just because a certain state has not ratified a treaty does not mean the treaty has not achieved the status of normative international law. For instance, Syria only acceded to the CW convention after its 2013 Ghouta Sarin strike; however, given both the otherwise near-universal adoption of the treaty, and state practice over the last century, most jurists would probably hold that any use of chemical weapons is a violation of IHL, even by a state which has not ratified the CW convention, and thus the Ghouta attack was an IHL violation (and a war crime). 

Another important issue for combatants and commentators alike to understand is who is governed by IHL, and how it’s enforced. Simply: like all international law, IHL does not apply to individuals, but to states (and nonstate actors who have effective governance of territory), and is enforced through the principle of reciprocity. Unfortunately, there’s no global “leviathan” capable of enforcing universal laws, so the rules-based order makes do with structures that seek to ensure states self-police. In other words, if you’re an American soldier and you commit a war crime, you’re not guilty of an IHL violation – the U.S. government is. However, you are probably still going to get prosecuted by the U.S. government for what you did, because U.S. laws are structured to comply with international law; if the U.S. government doesn’t comply with IHL, other states will be less inclined to do so (reciprocity), which would work against the interest of the U.S. government in a stable, predictable, and just rules-based international order. In this way, states “police their own” to ensure IHL is enforced (or at least that’s the way it’s supposed to work).     

What does it mean for me? At this point, a soldier, trainer, policymaker, or commentator may be wondering how IHL concerns them. For combatants, potential combatants, and those training them, understanding the principles of IHL is critical. In C2SI’s values-based approach, commitment to IHL is intertwined with a commitment to the values and principles of liberal democracy, which, like IHL, is underpinned by a commitment to human life and fundamental rights: strict compliance with IHL is a non-negotiable expectation of defenders of democracy and freedom. 

The basics of IHL compliance for combatants are straightforward in theory: don’t harm civilians, their property, enemy prisoners of war, the wounded, schools, places of worship, cultural sites, or hospitals. In practice, they can get complicated. An enemy soldier carrying a personal weapon, a tank, or a fortification is a clear legitimate target. What about an enemy cook in a rear area? A civilian who may be scouting your position or relaying messages? A government official? A civilian transporting fuel that will be sold to an enemy military? How do you deal with a building full of enemy fighters directly adjacent to a school full of kids? 

Most forces will have some sort of rules of engagement (ROE) to provide guidelines to their troops, but these do not excuse the individual fighter of his responsibility to internalize and follow the core principles of IHL and apply them in dialogue with both their survival instincts and their conscience. ROE are formulated and issued by military lawyers in offices far removed from decisions on the ground. If too restrictive, they can put fighters at risk of physical injury by failing to deal with threats; if too permissive, they put fighters at risk of moral injury – and prosecution – by implicitly encouraging potentially unnecessary and even illegal use of force (when the 15-6 comes down, it’s probably not going to be a JAGO who pays the price). 

From a practical standpoint, it’s also important for combatants to be “strategic corporals,” and understand how critical it is to comply with IHL and adhere to its principles. In our day and age, combatants from Syria to Ukraine to Artsakh to Gaza are operating in conflict environments where cameras and other sensors are everywhere and every action is potentially documented and instantly weaponizable as propaganda – or evidence. War, per Clausewitz, is an extension of political intercourse with the admixture of other means; in the current geopolitical context, the information space is almost as important as the battlespace in influencing political decisions and thus determining the outcome of war, and messaging is critical. An IHL violation – or even an act that might not technically be a violation, but which is seen as contrary to the principle of humanity – can result not only in harm to the conscience and professional and legal consequences, for the individual who causes or permits it, but can have second-and third-order effects up to the strategic level that can jeopardize the cause. Thus, it’s critical for those involved in conflict to take IHL compliance seriously – to treat it as part of the “protection” warfighting function. 

How can IHL be operationalized in training? As noted previously, IHL is a vast subject. One can take a semester-long graduate-level course on it and barely scratch the surface. No basic training course for potential combatants – especially a compressed one – has the time to explore it. 

However, while the devil is in the details, the principles are relatively straightforward and easy to grasp. A soldier or legally armed civilian doesn’t need to be able to cite line and verse with regards to this or that convention or be able to parse the distinction between an IAC and a NIAC (although a commentator, policymaker, or public affairs officer most certainly does). A good understanding of those core principles combined with knowledge of specific prohibitions and guidelines can be communicated in a couple of days’ training and should be developed through scenario-based classroom exercises just like any other basic skill. As trainees advance to more complex, practical training, trainers should incorporate IHL-related elements into the scenarios being trained. How does a drone operator react to a wounded enemy soldier? How does a squad leader react when one of his soldiers shoots a prisoner – and vice versa? How does a platoon leader account for issues of discrimination and proportionality in targeting when dealing with civilians on the battlefield? How does a battalion staff account for precaution when planning operations in a populated area? How do soldiers react to orders that may violate the principles of IHL? How can they promote the principle of humanity amidst the unforgiving environment of war? Depending on the level of the unit being trained, scenarios like these, and countless others, can and should be incorporated, and hot washes and after-action reviews in training should emphasize IHL-related, ethical, and moral issues every bit as much as the mechanistic, technical aspects of success on the battlefield. 

War is not only the ultimate test of strength but of commitment to our core principles as democratic, humanistic societies; compliance to IHL is necessary, though not sufficient, to pass the latter. There is a strong argument that the lethality of modern means and methods of warfare, and the sheer scale on which it can be conducted, make IHL, as currently established, insufficient to promote the principle of humanity amidst conflict. As we can see from the growing number of civilian casualties in the bombardment of Gaza, even organizations that take IHL compliance seriously (as, to its credit, the IDF generally does) can cause excessive levels of civilian harm. Even for those who strongly support Ukraine in its fight against Russian aggression, it’s difficult not to react with dismay to footage of Ukrainian drone operators callously finishing off wounded Russian soldiers, helplessly begging for their lives, with air-dropped grenades. And the U.S. wars of the last two decades have featured no shortage of egregious harm, from “signature strikes” to escalation-of-force incidents to detainee mistreatment, despite the generally earnest efforts of military bureaucracies to control the effects of the powerful systems at their disposal and comply with IHL. 

While movements to ban the use of explosive weapons in urban areas or arguments that combatants should generally accept higher levels of risk to themselves in order to reduce harm to others may gain little traction in the immediate future with many military professionals, policymakers, and commentators, progress can and should be made in these areas; for instance, policing (which exists on the same continuum as war) can be made demonstrably less lethal even when dealing with serious threats, by shifts in methods, means, attitudes and organizational culture, while mitigating risks to officers and achieving objectives of public safety. Likewise, the conduct of war can likely be made more humane by innovative approaches. Even at the squad level, armed defenders of democracy must seek to identify such approaches as they pursue mission success – and that starts with a solid grounding in IHL.             


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