International humanitarian law

International humanitarian law, also referred to as the laws of armed conflict, is the law that regulates the conduct of war. 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, 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.
While IHL concerns the rules and principles governing the conduct of warfare once armed conflict has begun, jus ad bellum pertains to the justification for resorting to war and includes the crime of aggression. Together the jus in bello and jus ad bellum comprise the two strands of the laws of war governing all aspects of international armed conflicts. The law is mandatory for nations bound by the appropriate treaties. There are also other customary unwritten rules of war, many of which were explored at the Nuremberg trials. IHL operates on a strict division between rules applicable in international armed conflict and internal armed conflict.
Since its inception, IHL has faced criticism for the fact that the foreseeable killing of large numbers of citizens can be considered compliant with IHL, and its creation largely by Western powers in service of their own interests. There is academic debate whether IHL, which is formally constructed as a system that prohibits certain acts, can also facilitate violence against civilians when belligerents argue that their attacks are compliant with IHL.

The law of Geneva and the law of The Hague

Contemporary IHL is made up of two historical streams:

The law of The Hague, referred to in the past as the law of war proper; and
The law of Geneva, or humanitarian law.

The two streams take their names from a number of international conferences that took place in those two cities and which produced treaties relating to war and conflict, in particular the Hague Conventions of 1899 and 1907, and the Geneva Conventions, the first of which was drawn up in 1863. Both deal with jus in bello, which deals with the question of whether certain practices are acceptable during armed conflict. While IHL concerns the rules and principles governing the conduct of warfare once armed conflict has begun, jus ad bellum pertains to the justification for resorting to war and includes the crime of aggression. Together the jus in bello and jus ad bellum comprise the two strands of the laws of war governing all aspects of international armed conflicts. The law is mandatory for nations bound by the appropriate treaties. There are also other customary unwritten rules of war, many of which were explored at the Nuremberg trials. IHL operates on a strict division between rules applicable in international armed conflict and internal armed conflict.
The law of The Hague, or the laws of war proper, "determines the rights and duties of belligerents in the conduct of operations and limits the choice of means in doing harm". In particular, it concerns itself with:

the definition of combatants;
establishes rules relating to the means and methods of warfare; and
examines the issue of military objectives.

Systematic attempts to limit the savagery of warfare only began to develop in the 19th century. Such concerns were able to build on the changing view of warfare by states influenced by the Age of Enlightenment. The purpose of warfare was to overcome the enemy state, which could be done by disabling the enemy combatants. Thus, "the distinction between combatants and civilians, the requirement that wounded and captured enemy combatants must be treated humanely, and that quarter must be given, some of the pillars of modern humanitarian law, all follow from this principle".

The law of Geneva

Fritz Munch sums up historical military practice before 1800: "The essential points seem to be these: In battle and in towns taken by force, combatants and non-combatants were killed and property was destroyed or looted." In the 17th century, the Dutch jurist Hugo Grotius, widely regarded as the founder or father of public international law, wrote that "wars, for the attainment of their objects, it cannot be denied, must employ force and terror as their most proper agents".

Humanitarian norms in history

Even in the midst of the carnage of history, however, there have been frequent expressions and invocation of humanitarian norms for the protection of the victims of armed conflicts: the wounded, the sick and the shipwrecked. These date back to ancient times.
In the Old Testament, the King of Israel prevents the slaying of the captured, following the prophet Elisha's admonition to spare enemy prisoners. In answer to a question from the King, Elisha said, "You shall not slay them. Would you slay those whom you have taken captive with your sword and with your bow? Set bread and water before them, that they may eat and drink and go to their master."
In ancient India there are records describing the types of weapons that should not be used: "When he fights with his foes in battle, let him not strike with weapons concealed, nor with barbed, poisoned, or the points of which are blazing with fire." There is also the command not to strike a eunuch nor the enemy "who folds his hands in supplication ... Nor one who sleeps, nor one who has lost his coat of mail, nor one who is naked, nor one who is disarmed, nor one who looks on without taking part in the fight."
Islamic law states that "non-combatants who did not take part in fighting such as women, children, monks and hermits, the aged, blind, and insane" were not to be molested. The first Caliph, Abu Bakr, proclaimed, "Do not mutilate. Do not kill little children or old men or women. Do not cut off the heads of palm trees or burn them. Do not cut down fruit trees. Do not slaughter livestock except for food." Islamic jurists have held that a prisoner should not be killed, as he "cannot be held responsible for mere acts of belligerency".
However, the prohibition against killing non-combatants is not necessarily absolute in Islamic Law. For example, in situations where an "enemy retreats inside fortifications and one-to-one combat is not an option", Islamic jurists have been unanimous as to the permissibility on the use of less discriminating weapons such as mangonels if required by military necessity but have differed with respect to the use of fire in such cases.

Codification of humanitarian norms

The most important antecedent of IHL is the current Armistice Agreement and Regularization of War, signed and ratified in 1820 between the authorities of the then Government of Great Colombia and the Chief of the Expeditionary Forces of the Spanish Crown, in the Venezuelan city of Santa Ana de Trujillo. This treaty was signed under the conflict of Independence, being the first of its kind in the West.
It was not until the second half of the 19th century, however, that a more systematic approach was initiated. In the United States, a German immigrant, Francis Lieber, drew up a code of conduct in 1863, which came to be known as the Lieber Code, for the Union Army during the American Civil War. The Lieber Code included the humane treatment of civilian populations in areas of conflict, and also forbade the execution of POWs.
At the same time, the involvement during the Crimean War of a number of such individuals as Florence Nightingale and Henry Dunant, a Genevese businessman who had worked with wounded soldiers at the Battle of Solferino, led to more systematic efforts to prevent the suffering of war victims. Dunant wrote a book, which he titled A Memory of Solferino, in which he described the horrors he had witnessed. His reports were so shocking that they led to the founding of the International Committee of the Red Cross in 1863, and the convening of a conference in Geneva in 1864, which drew up the first Geneva Convention for the Amelioration of the Condition of the Wounded in Armies in the Field.

The law of Geneva is directly inspired by the principle of humanity. It relates to those who are not participating in the conflict, as well as to military personnel hors de combat. It provides the legal basis for protection and humanitarian assistance carried out by impartial humanitarian organizations such as the ICRC. This focus can be found in the Geneva Conventions.

Geneva Conventions

Geneva Conventions of 1949

The Geneva Conventions are the result of a process that developed in a number of stages between 1864 and 1949. It focused on the protection of civilians and those who can no longer fight in an armed conflict. As a result of World War II, all four conventions were revised, based on previous revisions and on some of the 1907 Hague Conventions, and readopted by the international community in 1949. Later conferences have added provisions prohibiting certain methods of warfare and addressing issues of civil wars.
The first three Geneva Conventions were revised, expanded, and replaced, and the fourth one was added, in 1949.

The Geneva Convention for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field was adopted in 1864. It was significantly revised and replaced by the 1906 version, the 1929 version, and later the First Geneva Convention of 1949.
The Geneva Convention for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea was adopted in 1906. It was significantly revised and replaced by the Second Geneva Convention of 1949.
The Geneva Convention relative to the Treatment of Prisoners of War was adopted in 1929. It was significantly revised and replaced by the Third Geneva Convention of 1949.
The Fourth Geneva Convention relative to the Protection of Civilian Persons in Time of War was adopted in 1949.