The international law bearing on issues of Arab–Israeli conflict, which became a major arena of regional and international tension since the birth of Israel in 1948, resulting in several disputes between a number of Arab countries and Israel. There is an international consensus that some of the actions of the states involved in the Arab–Israeli conflict violate international law, but some of the involved states dispute this.

In the Six-Day War in 1967, Israel pre-empted what many Israeli leaders believed to be an imminent Arab attack and invaded and occupied territory that had itself been invaded and occupied by neighboring Egypt, Syria and Jordan in the 1948 Arab–Israeli War. Following the peace treaties between Israel and Egypt and Israel and Jordan, in which the states relinquished their claims to the Israeli-occupied territory, the conflict today mostly revolves around the Palestinians.

The main points of dispute (also known as the "core issues" or "final status issues") are the following: Israel's annexation of East Jerusalem (Israel has also annexed the Golan Heights, but that territory is not claimed by Palestinians), construction of Israeli settlements in the Palestinian territories, and the erection of the Israeli West Bank barrier; how borders should be decided between Israel and a Palestinian state; the right of return of the Palestinian refugees from the 1948 and 1967 wars.

Customary international law Unlike a treaty agreement, customary international law is usually not written. Customs of a longstanding nature can be codified by formal treaties. The Laws and Customs of War on Land (Hague Convention IV) of 18 October 1907 and the Geneva Conventions of 12 August 1949 are examples of conventional laws that are declarations of customary law.Statute of the International Criminal Tribunal for the former Yugoslavia, Security Council Resolution 827, 25 May 1993 The drafters of the Statute had explicitly declined to make it a self-contained criminal code. They instead granted the Tribunal jurisdiction over a set of very broadly defined crimes, the specific content of which was to be found in customary international law. Though the Tribunal recognized that binding conventional law could also provide the basis for its jurisdiction, it has in practice always determined that the treaty provisions in question are also declaratory of custom. To prove that a certain rule is customary one has to show that it is reflected in state practice and that there exists a conviction in the international community that such practice is required as a matter of law. In this context, "practice" relates to official state practice and therefore includes formal statements by states. A contrary practice by some states is possible because if this contrary practice is condemned by the other states, or subsequently denied by the government itself, the original rule is actually confirmed.

In accordance with article 13 of the UN Charter, the General Assembly is obligated to initiate studies and to make recommendations that encourage the progressive development of international law and its codification. Acting in that agreed-upon treaty capacity, the General Assembly affirmed the principles of international law that were recognized by the Charter of the Nuremberg Tribunal and directed that they should be codified.See General Assembly Resolution 95 (I), 11 December 1946, and UN General Assembly Resolution 177. Many of those same principles were subsequently adopted for inclusion in draft treaties that were under development by the International Law Commission of the United Nations. They were also incorporated through the agreement of the High Contracting Parties into the Geneva Conventions of 1949.see Nuremberg Principles and In 1993 the UN Security Council "acting under Chapter VII of the Charter on the United Nations" established an international tribunal and approved a Statute that had been recommended in a report submitted by the UN Secretary-General. It concluded beyond doubt that the law applicable in armed conflict as embodied in the Geneva Conventions of 12 August 1949 and the Hague Convention (IV) of 18 October 1907 had become part of international customary law, and should be part of the subject matter jurisdiction of the International Criminal Tribunal for the former Yugoslavia. In 1998, the United Nations Diplomatic Conference of Plenipotentiaries approved the Rome Statute of the International Criminal Court. The offenses against unwritten customary international law were amenable to prosecution by international tribunals, like the Nuremberg Tribunal, long before they were codified and incorporated into the subsequent treaties.

Conventions, resolutions and declarations Many provisions of international law are based upon principles and norms that were developed in the Americas during the 19th century. They include the principle of uti possidetis of 1810 and the related Monroe Doctrine of 1823, regarding non-colonization and non-intervention. In 1890, the First International Conference of American States adopted a proscription against territorial conquest and agreed upon the non-recognition of all acquisitions made by force. Those principles and regional understandings were recognized in Article 21 of the Covenant of the League of Nations. The system of mandates contained in article 22 of the Covenant was based in part upon those normative declarations and state practices. The Kellogg–Briand Pact of 1928, and the League of Nations approval of the Stimson Doctrine in 1931 were efforts designed to end the practice of coercive territorial revisionism through international law.

After World War II, the principles of international law that upheld the territorial integrity of states were incorporated in the Charter of the United Nations, and subsequently reaffirmed in the Declaration on the Granting of Independence to Colonial Countries and Peoples, the Organization of African Unity charter respecting the integrity of inherited boundaries, and the 1975 CSCE Helsinki Final Act which contained a proscription that boundaries could only be altered by consent.International Law and International Relations, Beth A. Simmons and Richard H. Steinberg, Cambridge University Press, 2007, , pp. 278–279 The Chapter on Fundamental Rights and Duties of States in the Charter of the Organization of American States provides that:The territory of a State is inviolable; it may not be the object, even temporarily, of military occupation or of other measures of force taken by another State, directly or indirectly, on any grounds whatever. No territorial acquisitions or special advantages obtained either by force or by other means of coercion shall be recognized.

Legal issues related to sovereignty In their relations with other peoples and countries during the colonial era the Concert of Europe adopted a fundamental legal principle that the supreme legal authority, or sovereignty, lay outside the indigenous nations. That legal principle resulted in the creation of a large number of dependent states with restricted sovereignty or colonial autonomy. Various terms were used to describe different types of dependent states, such as condominium, mandate, protectorate, colony, and vassal state. After World War II there was strong international pressure to eliminate dependencies associated with colonialism.see The Declaration Regarding Non-Self-Governing Territories, in Chapter XI of the UN Charter, and The Declaration on the Granting of Independence to Colonial Countries and Peoples, General Assembly Resolution 1514 (XV)

The vast majority of the world's sovereign states resulted from the grant of independence to colonial peoples and dependent territories. Prior to World War II many states were formed as a result of wars that were resolved through peace treaties. Some of these peace treaties were imposed on the losing side in a war; others came about as a result of negotiations that followed wars, or were entered into under the threat of war. In these cases, the applicable law was bound in peace treaties among the states. The practice of territorial aggrandizement was prohibited by the UN Charter, a multilateral treaty, and the authoritative explanation of its legal principles contained in UN General Assembly resolution 2625 (XXV) of 24 October 1970, Declaration of Principles of International Law Concerning Friendly Relations and Co-operation Among States in Accordance with the Charter of the United Nations. The purpose of the United Nations is the prevention and removal of threats to peace and the suppression of acts of aggression. The Charter requires that members shall refrain from the threat of, or use of force. According to communis opinio the obligations imposed by those provisions of the Charter have become part of customary international law and are binding on all States, whether they are members of the United Nations or not.The International Law Commission's Draft Articles on State Responsibility: Part 1, Articles 1–35, By United Nations International Law Commission, Compiled by Shabtai Rosenne, Martinus Nijhoff Publishers, 1991, , p. 189

Treaties and resolutions The communities and Holy Places of Palestine have been under the express protection of international law since the early 19th century. For example, the International Court of Justice advisory opinion noted that access to the Christian, Jewish and Islamic Holy Places had been protected by various laws dating back to the early Ottoman Empire, with the latest provisions having been incorporated into the UN Partition Plan, article 13 of the League of Nations Mandate, and Article 62 of the Treaty of Berlin of 13 July 1878.

The Treaty of Paris in 1814 called for a congress of the Great Powers of Europe to settle the future boundaries of the continent. Nearly every state in Europe was represented, and among other things a prohibition on unilateral annexation was adopted. This bolstered the concept of territorial integrity, which was enshrined in the Congress of Vienna in 1815. Benvenisti, Eyal, The Origins of the Concept of Belligerent Occupation. Law and History Review 26.3 (2008): 46 pars. 1 Jul. 2009

The 1856 Treaty of Paris declared that the Sublime Porte, the government of the Ottoman Empire, had been admitted to participate in the Public Law and System (Concert) of Europe.International Law: Achievements and Prospects, by Mohammed Bedjaoui (Editor), UNESCO, Martinus Nijhoff, 1991, , p. 7 The European system of public law governed territorial accessions and the creation of new states. After the Russo-Turkish Wars in 1878, Russia and the Ottoman Empire concluded the Treaty of San Stefano. Because it modified the terms of the Treaty of Paris of 1856, the other signatories called for a Congress to obtain its revision. The Treaty of Berlin of 1878 was the result. Montenegro, Serbia, and Romania were recognized as new independent states and granted specific territory on condition that religious, political, and property rights of minorities were guaranteed on a nondiscriminatory basis.See Defending the Rights of Others: The Great Powers, the Jews, and International Minority Protection, 1878–1938, Carole Fink, Cambridge University Press, 2006, , p. 37 The delegates of the First Zionist Congress acknowledged these customary diplomatic precedents in the Basle Program. It stated that the aim of Zionism was the creation of a home for the Jewish people in Palestine, secured by public law.

During the course of the British mandate in Palestine, the British government sought to reconcile the two claims in different ways. A number of proposals and declarations were put forward, all of which were rejected by one party or the other, and usually both. Again, two different interpretations apply: