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 participating 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 or 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, concerning 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 (jus in bello) 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.

International humanitarian law is traditionally seen as distinct from international human rights law (which governs the conduct of a state towards its people), although the two branches of law are complementary and in some ways overlap.

The Law of Geneva and The Law of The Hague

Modern international humanitarian law is made up of two historical streams:

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

The two streams take their names from several international conferences which drew up 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.

The Law of The Hague or the laws of war was proper, "determines the rights and duties of belligerents in the conduct of operations and limits the choice of means in harming". 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".

Geneva Conventions

The Geneva Conventions are the result of a process that developed in many 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 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.

There are three additional amendment protocols to the Geneva Convention:

1. Protocol I (1977): Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts. As of 12 January 2007, it had been ratified by 167 countries.
2. Protocol II (1977): Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of Non-International Armed Conflicts. As of 12 January 2007, it had been ratified by 163 countries.
3. Protocol III (2005): Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Adoption of an Additional Distinctive Emblem. As of June 2007, it had been ratified by seventeen countries and signed but not yet ratified by an additional 68.

The Geneva Conventions of 1949 may be seen, therefore, as the result of a process that began in 1864. Today they have "achieved universal participation with 194 parties". This means that they apply to almost any international armed conflict. The Additional Protocols, however, have yet to achieve near-universal acceptance, since the United States and several other significant military powers (like Iran, Israel, India, and Pakistan) are currently not parties to them.

Principles in International Humanitarian Law

There are two main principles in IHL; the principle of distinction dictates that combatants and non-combatants must be treated differently and the principle of not causing disproportionate suffering to combatants. In Legality of the Threat or Use of Nuclear Weapons, the ICJ described these concepts as "intransgressible principles of international customary law".

The two Hague Conventions of 1899 and 1907 considered restrictions on the conduct of war and the Geneva Conventions of 1949, which were organised by the International Committee of the Red Cross, considered the protection of innocent parties in conflict zones. The First Geneva Convention covers wounded and ill combatants, the Second Geneva Convention covers combatants at sea who are wounded, ill, or shipwrecked, the Third Geneva Convention covers prisoners of war and the Fourth Geneva Convention covers civilians.

These conventions were supplemented the Additional Protocol I and Protocol II, which were codified in 1977. Initially, IHL conventions were only considered to apply to a conflict if all parties had ratified the relevant convention under the clause, but this posed concerns and the Martens clause began to be implemented, providing that the law would generally be deemed to apply.

There have been various agreements to outlaw particular types of weapons, such as the Chemical Weapons Convention and the Biological Weapons Convention. The use of nuclear weapons was determined to conflict with the principles of IHL by the ICJ in 1995, although the court also held that it "cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defense." Multiple treaties have attempted to regulate the use of these weapons, including the Non-Proliferation Treaty and the Joint Comprehensive Plan of Action, but key states have failed to sign or have withdrawn. There have been similar debates on the use of drones and cyberwarfare on the international stage.

International Criminal Law

International criminal law sets out the definition of international crimes and compels states to prosecute these crimes. While war crimes were prosecuted throughout history, this has historically been done by national courts. The International Military Tribunal in Nuremberg and the International Military Tribunal for the Far East in Tokyo were established at the end of World War II to prosecute key actors in Germany and Japan.

The jurisdiction of the tribunals was limited to crimes against peace (based on the Kellogg–Briand Pact), war crimes (based on the Hague Conventions), and crimes against humanity, establishing new categories of international crime. Throughout the twentieth century, the separate crimes of genocide, torture, and terrorism were also recognised.

Initially, these crimes were intended to be prosecuted by national courts and subject to their domestic procedures. The Geneva Conventions of 1949, the Additional Protocols of 1977, and the 1984 UN Convention against Torture mandated that the national courts of the contracting countries must prosecute these offenses where the perpetrator is on their territory or extradite them to any other interested state.

It was in the 1990s that two ad hoc tribunals, the International Criminal Tribunal for the Former Yugoslavia (ICTY) and the International Criminal Tribunal for Rwanda (ICTR), were established by the UNSC to address specific atrocities. The ICTY had authority to prosecute war crimes, crimes against humanity and genocide occurring in Yugoslavia after 1991 and the ICTR had authority to prosecute genocide, crimes against humanity and grave breaches of the 1949 Geneva Conventions during the 1994 Rwandan genocide.

The International Criminal Court (ICC), established by the 1998 Rome Statute, is the first and only permanent international court to prosecute genocide, war crimes, crimes against humanity, and crimes of aggression. There are 123 state parties to the ICC although several states have declared their opposition to the court; it has been criticized by African countries including.

The Gambia and Kenya for "imperialist" prosecutions. One particular aspect of the court that has received scrutiny is the principle of complementarity, whereby the ICC only has jurisdiction if the national courts of a state with jurisdiction are "unwilling or unable to prosecute" or where a state has investigated but chosen not to prosecute a case.

The United States has a particularly complicated relationship with the ICC; originally signing the treaty in 2000, the US stated in 2002 that it did not intend to become a party as it believed the ICC threatened its national sovereignty and the country does not recognize the court's jurisdiction.

Role of NGO in International Humanitarian Law

A non-governmental organization (NGO, also often referred to as "civil society organization" or CSO) is a not-for-profit group, principally independent from the government, which is organized on a local, national, or international level to address issues in support of the public good. Task-oriented and made up of people with a common interest, NGOs perform a variety of services and humanitarian functions, bring public concerns to governments, monitor policy and program implementation, and encourage the participation of civil society stakeholders at the community level. Some are organized around specific issues, such as human rights.

Case Study: Tokyo Trial

"International Military Tribunal" redirects here. For the Tokyo Trial, see the International Military Tribunal for the Far East.

The Allies held the Nuremberg trials against representatives of the defeated Nazi Germany for plotting and carrying out invasions of other countries across Europe and atrocities against their citizens in World War II.

Between 1939 and 1945, Nazi Germany invaded many countries across Europe, inflicting 27 million deaths in the Soviet Union alone. Proposals for how to punish the defeated Nazi leaders ranged from a show trial (the Soviet Union) to summary executions (the United Kingdom). In mid-1945, France, the Soviet Union, the United Kingdom, and the United States agreed to convene a joint tribunal in Nuremberg, occupied Germany, with the Nuremberg Charter as its legal instrument.

Between 20 November 1945 and 1 October 1946, the International Military Tribunal (IMT) tried 22 of the most important surviving leaders of Nazi Germany in the political, military, and economic spheres, as well as six German organizations. The purpose of the trial was not just to convict the defendants but also to assemble irrefutable evidence of Nazi crimes, offer a history lesson to the defeated Germans, and delegitimize the traditional German elite.

The IMT verdict followed the prosecution declaring the crime of plotting and waging aggressive war "the supreme international crime" because "it contains within itself the accumulated evil of the whole". Most of the defendants were also charged with war crimes and crimes against humanity, and the systematic murder of millions of Jews in the Holocaust was significant to the trial.

The United States conducted twelve further trials against lower-level perpetrators, which focused more on the Holocaust. Controversial at the time for their retroactive criminalization of aggression, the trials' innovation of holding individuals responsible for violations of international law is considered "the true beginning of international criminal law".