Traditionally, international law governed relations between nations exclusively. Individuals did not have international legal rights. They were objects, not subjects of international law. To the extent that states owed obligations to individuals, such obligations derived from the individual's nationality and were owed to the individual's nation. A state could seek redress for the treatment of its citizens in a foreign state via the international legal system, but the system did not protect domestic citizens of a state from their own state. However, international law recognized the doctrine of humanitarian intervention, which justified the use of force against a state which maltreated its own citizens. Although this doctrine could be used as a pretext for one nation to invade another, it was the first to limit a state's freedom under international law in the treatment of its own citizens.
International law has long recognized the ability of states to limit their own sovereignty by treaty. In so doing, a subject that was not governed by international law becomes international. This principle has been instrumental in the development of international human rights law, as illustrated by early human rights treaties.
Other precursors to the modern human rights system include the League of Nations Mandate system (continued by the U.N. trusteeship system) which administered former colonies of states which lost World War I, with the view that the well being of native populations was a sacred trust. By 1994, there were no more such trust territories. World War I also resulted in the redrawing of borders and the creation of new states and minority populations. The victororious nations insisted that the new states protect such minorities by means of a series of treaties concluded after the war. The League of Nations acted as guarantor of these treaty obligations and developed a system for handling violations of minority rights. The League of Nations also established the International Labour Organization (ILO), which is now a specialized agency of the U.N. International labor standards have influenced the development of international human rights law and trade law. State responsibility for injury to aliens is an old doctrine of international law, consistent with the idea that individuals were not subjects of international law and states' obligations to individuals derived from their nationality. However, under this doctrince, general principles, such as minimum standards of justice, developed and contributed to modern human rights law. The state responsibility doctrine remains relevant today in diplomatic relations.
Early human rights protection efforts focused on holding nations accountable for human rights violations. However, it soon became evident that it was necessary to hold individuals and other private entities accountable. International criminal law imposes individual responsibility for international crimes, but there was no permanent international court with jurisdiction to apply the law. Up until recently, criminal courts were established to handle specific situations, such as the Nuremberg War Crimes Tribunal and the International Criminal Tribunals for the Former Yugoslavia and Rwanda in 1993-4. The Statute of the International Criminal Court was adopted in 1998 by U.N. diplomatic conference and entered into force in 2002.
International humanitarian law has also influenced the development of international human rights law and is actually much older than human rights law. It is the human rights component of law of armed conflict and relates, for example, to the treatment of injured combatants and prisoners of war. Today, the law of armed conflict is codified in the four Geneva Conventions.
International human rights law began with the protection of certain groups i.e. slaves, minorities, certain native populations, foreign nationals and armed combatants. The legal fiction that injury suffered by an alien abroad was an injury to the state of the alien’s nationality left citizens unprotected by their own state. Modern international human rights law differs most from earlier international law doctrines by recognizing that all individuals have basic human rights as individuals, not as nationals of a particular state. Buergenthal, Shelton & Stewart, International Human Rights in a Nutshell, 4th ed. (West, 2009) K3240.4 .B84 2009.
The main sources of international human rights law are treaties. The following important treaties and treaty provisions are known as the “international bill of human rights”.
Although it is not technically a treaty, the UDHR is extremely important as "the first comprehensive human rights instrument to be proclaimed by a global international organization". Buergenthal, Shelton & Stewart, International Human Rights in a Nutshell at 40 K3240.4 .B84 2017.
For many, the U.N. Charter provisions fell short of expectations in terms of human rights protection. For political reasons, proposals that an international bill of rights be appended to the U.N. Charter were made but not acted upon. The newly created Commission on Human Rights opted for a declaration rather than a legally binding treaty. It decided to issue the declaration first and take up the drafting of human rights treaties soon thereafter. However, it took many years for the two covenants ("ICCPR" and "ICESCR") to come into existence. They were opened for signature in 1966 but it took over a decade for the requisite 35 states to ratify them and for the treaties to enter into force.
In the interim, the UNDHR has often been used to interpret Articles 55 and 56 of the U.N. Charter. The reliance on the UNDHR has given rise to the view that it is now an authoritative interpretation of these UN Charter provisions or at least customary international law or a general principle of law. Id at 42-46.
While international treaties and customary law form the backbone of international human rights law, U.N. resolutions, decisions of human rights bodies (i.e. U.N. Human Rights Committee), national laws and court decisions are important as persuasive authority. In addition, "soft law", such as the declarations, guidelines and principles adopted at the international level contribute to the understanding, implementation and development of international human rights law. Soft law has been defined as non-binding documents or instruments (guidelines, declarations or principles) that may have use politically but are not enforceable. Hoffman, Marci & Rumsey, Mary, International and Foreign Legal Research: a coursebook (Martinus Nijhoff Publishers, 2008 later editions available as ebooks) K85 .H64 2008 at p. 7. See Introduction and U.N. Documents Research (IGOs) tabs for further discussion of soft law.