Military necessity in the context of "Armed conflict"

A war crime is a violation of the laws of war that gives rise to individual criminal responsibility for actions by combatants in action, such as intentionally killing civilians or intentionally killing prisoners of war, torture, taking hostages, unnecessarily destroying civilian property, deception by perfidy, wartime sexual violence, pillaging, and for any individual that is part of the command structure who orders any attempt to committing mass killings (including genocide or ethnic cleansing), the granting of no quarter despite surrender, the conscription of children in the military, and flouting the legal distinctions of proportionality and military necessity.

The formal concept of war crimes emerged from countries fighting and the codification of the customary international law that applied to warfare between sovereign states, such as the Lieber Code (1863) of the Union Army in the American Civil War and the Hague Conventions of 1899 and 1907 for international war. In the aftermath of World War II, the war-crime trials of the leaders of the Axis powers established the Nuremberg principles, such as that international criminal law defines what is a war crime. In 1899, the Geneva Conventions legally defined new war crimes and established that states could exercise universal jurisdiction over war criminals. In the late 20th century and early 21st century, international courts extrapolated and defined additional categories of war crimes applicable to a civil war.

The law of war is the part of international law that regulates the conditions for initiating war (jus ad bellum) and the conduct of hostilities (jus in bello). Laws of war define sovereignty and nationhood, states and territories, occupation, and other critical terms of law. Among other issues, the modern laws of war address the declarations of war; acceptance of surrender and the treatment of prisoners of war; the principles of distinction, as well as military necessity and proportionality; and the prohibition of certain weapons that cause unnecessary or excessive suffering.

The law of war is considered distinct from other bodies of law—such as the domestic law of a particular belligerent to a conflict—which may provide additional legal limits to the conduct or justification of war. The term law of war, or jus in bello, overlaps to some degree with opinio juris (also referred to as customary law), but refers to a very specific body of international law composed of customary and treaty-based law.

Distinction (principle of distinction) is a principle under international humanitarian law governing the legal use of force in an armed conflict, whereby belligerents must distinguish between combatants and protected civilians. Combatant in this instance means persons entitled to directly participate in hostilities and thus are not afforded immunity from being directly targeted in situations of armed conflict. Protected civilian in this instance means civilians who are enemy nationals or neutral citizens outside of the territory of a belligerent power.

Article 51.3 of the 1977 Additional Protocol I to the Geneva Conventions explains that “civilians shall enjoy the protection afforded by this section, unless and for such time as they take a direct part in hostilities.” Distinction, proportionality, and precaution are important factors in assessing military necessity in that the harm caused to protected civilians or civilian property must be proportional and not "excessive in relation to the concrete and direct military advantage anticipated" by an attack on a military objective.

Proportionality is a general principle in law which covers several separate (although related) concepts:

• The concept of proportionality is used as a criterion of fairness and justice in statutory interpretation processes, especially in constitutional law, as a logical method intended to assist in discerning the correct balance between the restriction imposed by a corrective measure and the severity of the nature of the prohibited act.
• Within criminal law, the concept is used to convey the idea that the punishment of an offender should fit the crime.
• Under international humanitarian law governing the legal use of force in an armed conflict, proportionality and distinction are important factors in assessing military necessity.
• Under the United Kingdom's Civil Procedure Rules, costs must be "proportionately and reasonably incurred", or "proportionate and reasonable in amount", if they are to form part of a court ruling on costs.

The principle of proportionality means that belligerents must not launch an attack when the anticipated death and injury to civilians is clearly excessive in light of the military advantage expected from the attack.

International humanitarian law (IHL), also referred to as the laws of armed conflict, is the law that regulates the conduct of war (jus in bello). It is a branch of international law that seeks to limit the effects of armed conflict by protecting persons who are not participants in hostilities and by restricting and regulating the means and methods of warfare available to combatants.

International humanitarian law is inspired by considerations of humanity and the mitigation of human suffering. It comprises a set of rules, which is established by treaty or custom and that seeks to protect persons and property/objects that are or may be affected by armed conflict, and it limits the rights of parties to a conflict to use methods and means of warfare of their choice. Sources of international law include international agreements (the Geneva Conventions), customary international law, general principles of nations, and case law. It defines the conduct and responsibilities of belligerent nations, neutral nations, and individuals engaged in warfare, in relation to each other and to protected persons, usually meaning non-combatants. It is designed to balance humanitarian concerns and military necessity, and subjects warfare to the rule of law by limiting its destructive effect and alleviating human suffering. Serious violations of international humanitarian law are called war crimes.

A war crime is a serious violation of the laws and customs applicable in armed conflict, known as international humanitarian law (IHL) and the laws of war, which gives rise to criminal responsibility under international law. Examples of actions committed by combatants in the conduct of war that can give rise to individual criminal responsibility include, but are not limited to: intentionally killing civilians, torture, taking hostages, unnecessarily destroying civilian property, deception by perfidy, wartime sexual violence, pillaging, the granting of no quarter despite surrender, the conscription of children in the military, ordering any attempt to commit mass killings (including genocide or ethnic cleansing), and flouting the requirements of distinction, proportionality and military necessity.

The formal concept of war crimes emerged from countries fighting and the codification of the customary international law that applied to warfare between sovereign states, such as the 1863 Lieber Code of the Union Army in the American Civil War and the Hague Conventions of 1899 and 1907 for international war. In the aftermath of the Second World War, the war crime trials of the leaders of the Axis powers established the Nuremberg principles, such as that international criminal law defines what is a war crime. In 1899, the Geneva Conventions legally defined new war crimes and established that states could exercise universal jurisdiction over war criminals. In the late 20th century and early 21st century, international courts extrapolated and defined additional categories of war crimes applicable to a civil war.