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:
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. 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. 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. 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.
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. 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.
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.
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 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.
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. 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. 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:
After World War II, the British government decided to abandon its mandate in Palestine. A United Nations Commission (UNSCOP) was assigned to recommend a solution to the conflict to the General Assembly. The recommendation was a partition plan that would result in an Arab and a Jewish state in the remaining mandate, and Jerusalem under UN rule, was approved by the General Assembly.
However, the resolution served partially as a basis for the Declaration of the Establishment of the State of Israel to take effect when Great Britain's mandate expired. Many states granted the State of Israel either de facto or de jure recognition. Israel was accepted as a sovereign member state in the United Nations and has diplomatic relations with many, but not all, sovereign states.
Several events have affected the legal issues related to the conflict:
Sovereign states have the right to defend themselves against overt external aggression, in the form of an invasion or other attack. A number of states assert that this principle extends to the right to launch military actions to reduce a threat, protect vital interests, or pre-empt a possible attack or emerging threat.
Security Council resolution 242, emphasized "the inadmissibility of the acquisition of territory by war," setting the stage for controversy on the legal status of areas captured in 1967, and in 1948.
There are two interpretations of this matter:
The Geneva Conventions and other international tractates recognize that land a) conquered in the course of a war; and b) the disposition of which is unresolved through subsequent peace treaties is "occupied" and subject to international laws of war and international humanitarian law. This includes special protection of individuals in those territories, limitations on the use of land in those territories, and access by international relief agencies.
Recognizing the controversial nature of sovereignty over Jerusalem, UNSCOP recommended that the city be placed under United Nations administration in the partition plan. This was approved by the General Assembly in November 1947, accepted by the Jews and rejected by the Arabs. However, the 1948-1949 war resulted in Israel occupying the western portion of the city. Israel made Jerusalem its capital in 1950, establishing governmental offices in areas it controlled. Soon afterward in 1950, Jordan annexed the eastern part along with the remainder of the West Bank.
After the 1967 war, Israel put the parts of Jerusalem that had been captured during the war under its jurisdiction and civilian administration, establishing new municipal borders. Arguing that this did not amount to annexation at the time, subsequent legal actions have been interpreted as consistent with an annexation.
On July 30, 1980, the Knesset passed a basic law making "Jerusalem, complete and united...the capital of Israel." Since then Israel has extended the municipal boundaries several times.
International bodies such as the United Nations have condemned Israel's Basic Law concerning Jerusalem as a violation of the Fourth Geneva Convention and therefore hold that the establishment of the city as Israel's capital is against international law. Consequently, countries have established embassies to Israel's government outside of Jerusalem. Similarly, missions to the Palestinian National Authority are at the insistence of Israel's government located outside of Jerusalem.
Israel has filed strenuous protests  against this policy, asserting that:
In its 2004 advisory opinion on the legality of the Israeli West Bank barrier, the International Court of Justice concluded that the lands captured by Israel in the 1967 war, including East Jerusalem, are occupied territory.
Article 49 of the Fourth Geneva Convention states in paragraph 1, 
Individual or mass forcible transfers, as well as deportations of protected persons from occupied territory to the territory of the Occupying Power or to that of any other country, occupied or not, are prohibited, regardless of their motive.
and states in paragraph 6,
The Occupying Power shall not deport or transfer parts of its own civilian population into the territory it occupies.
Arguments supporting the position that establishing, funding, or allowing settlements in the territories is a violation of international law are,
Arguments supporting the position that settlement in the territories does not violate international law are,
Israel has completed long stretches of barriers within the West Bank, separating Israel proper, Israeli settlements and large parts of the Palestinian territories from Palestinian cities and population centers.
In 2004, the United Nations passed a number of resolutions and the International Court of Justice issued a ruling where judges ruled 14-1 that the portions of the Israeli West Bank barrier that are located within occupied Palestinian territories are illegal under international law. Prior to the ruling, Israel had made the claim that the ICJ lacked standing to rule on the legality of the barrier, which the court unanimously rejected. On July 20, 2004, the United Nations General Assembly passed a resolution demanding that Israel obey the ICJ ruling. 150 nations voted in favor of the resolution, 7 voted against, and 10 abstained.
The construction by Israel, the occupying power, of a wall in the Occupied Territories departing from the armistice line of 1949 is illegal under relevant provisions of international law and must be ceased and reversed.
The United Kingdom, Germany, Bulgaria, and Cameroon abstained from the vote. The justification given by the U.S. for the veto was that the resolution did not condemn terrorist attacks made by Palestinian groups (see Negroponte doctrine). The United States, however, has been condemned by some countries for its support of the barrier.
One week later, on October 21, a similar (though non-binding) resolution (ES-10/13) was passed by the UN General Assembly 144-4 with 12 abstentions. The resolution said the barrier was "in contradiction to international law", and demanded that Israel "stop and reverse" its construction. Israel called the resolution a "farce".
In December 2003, the United Nations General Assembly passed a resolution requesting the International Court of Justice (ICJ) to make a non-binding advisory opinion on the "legal consequences arising" from the construction of the barrier.
The hearings began in February 2004. The Palestinian Authority is not a member of the court but was allowed to make a submission by virtue of being a UN observer and a co-sponsor of the General Assembly resolution. In January 2004, the court also authorized the League of Arab States and the Organisation of the Islamic Conference to make submissions.
Israel initially announced that it would cooperate with the court, while noting that advisory rulings of the ICJ are not binding. Israel later made a written submission to the court rejecting the authority of the court to rule on the case, but announced (on February 12, 2004) that it would not appear at the court to make oral submissions.
On January 30, 2004, Israel announced officially it did not recognize ICJ authority to rule over the barrier issue. Israel also dispatched a 120-page document, elaborating on the security needs to build the "terror prevention fence" and purporting to demonstrate the atrocities committed by Palestinian terrorists. The document also included a judicial part with legal accounts supporting Israel's claim that the issue of the barrier is political and not in the ICJ authority.
On July 9, 2004, the International Court of Justice issued its opinion against the barrier, calling for it to be removed and the Arab residents to be compensated for any damage done. The Court advised that the United Nations General Assembly, which had asked for the ruling, and the Security Council should act on the issue.
A summary of the ruling is as follows:
The opinion was passed 14-1 by the court judges, except for the 4th decision which was passed 13-2.
Thomas Buergenthal, the American judge, was the sole dissenting member of the 15 judges on this ICJ panel. In his declaration, he stated that there was much in the court's opinion with which he agreed but that the court should have declined to hear the case since it did not have before it "relevant facts bearing directly on issues of Israel's legitimate right of self-defense". He stated that his dissenting opinion "should not be seen as reflecting my view that the construction of the wall by Israel on the Occupied Palestinian Territory does not raise serious questions as a matter of international law." On the point of portions of the wall that were being built beyond the green line, which Israel stated were to defend settlements, Buergenthal stated:
Paragraph 6 of Article 49 of the Fourth Geneva Convention also does not admit exceptions on grounds of military or security exigencies. It provides that "the Occupying Power shall not deport or transfer parts of its own civilian population into the territory it occupies". I agree that this provision applies to the Israeli settlements in the West Bank and that their existence violates Article 49, paragraph 6. It follows that the segments of the wall being built by Israel to protect the settlements are ipso facto in violation of international humanitarian law. Moreover, given the demonstrable great hardship to which the affected Palestinian population is being subjected in and around the enclaves created by those segments of the wall, seriously doubt that the wall would here satisfy the proportionality requirement to qualify as a legitimate measure of self-defence.
The opinion was accepted by the United Nations General Assembly, on July 20, 2004, it passed a resolution demanding that Israel obey the ICJ ruling.  Israel, the US, Australia, the Federated States of Micronesia, the Marshall Islands, and Palau voted against the resolution, 10 nations abstained, and 150 nations voted in favor.
Palestinian leader Yasser Arafat said: "This is an excellent decision. This is a victory for the Palestinian people and for all the free peoples of the world."
Israel rejected the ICJ ruling and emphasized the barrier's self-defense aspect , and stressed that Israel will continue to build the barrier. The United States also rejected the ruling, declaring that the issue was of political rather than legal nature. Colin Powell stated that barrier was effective against terror, and noted that the ICJ ruling was not binding, but insisted that Israel not use the barrier to predetermine permanent borders. 
Numerous human rights organizations welcomed the ICJ ruling. Amnesty International said that Israel should immediately cease constructing the barrier. The governments of Israel's neighbors Lebanon, Syria, Jordan, and Egypt also welcomed the ruling.
On July 13, 2004, the US House of Representatives passed Resolution HR 713 deploring "the misuse of the International Court of Justice (ICJ)... for the narrow political purpose of advancing the Palestinian position on matters Palestinian authorities have said should be the subject of negotiations between the parties."  The Resolution further stated that twenty-three countries, including every member of the G8 and several other European states, had "submitted objections on various grounds against the ICJ hearing the case."
... a person who is outside his/her country of nationality or habitual residence; has a well-founded fear of persecution because of his/her race, religion, nationality, membership in a particular social group or political opinion; and is unable or unwilling to avail himself/herself of the protection of that country, or to return there, for fear of persecution. The convention is administered by the United Nations High Commissioner for Refugees (UNHCR).
The United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA), which was established prior to the 1951 convention in response to the humanitarian crisis, applies a different definition:
Under UNRWA's operational definition, Palestine refugees are persons whose normal place of residence was Palestine between June 1946 and May 1948, who lost both their homes and means of livelihood as a result of the 1948 Arab-Israeli conflict. UNRWA's services are available to all those living in its area of operations who meet this definition, who are registered with the Agency and who need assistance. UNRWA's definition of a refugee also covers the descendants of persons who became refugees in 1948.
Since the definition used by UNRWA was originally made on an operational basis rather than dictated by specific international law, obligations and rights related to Palestinian refugees under international law are a matter of some debate. The debate centers on questions such as: whether the status of refugees can properly be passed through inheritance to individuals who have never lived in the vacated areas, and whether individuals who have repatriated in other countries can legally claim refugee status.
Palestinian refugees were excluded from the 1951 Convention due to the clause that "This Convention shall not apply to persons who are at present receiving from organs or agencies of the United Nations other than the United Nations High Commissioner for Refugees protection or assistance." As interpreted by UNHCR, this caused some anomalies, since UNRWA admits some persons as refugees that are not automatically admitted by the Convention, and, conversely, some of the legal protections given to refugees by the Convention were not available to most Palestinians. In 2002, UNHCR adopted a revised interpretation that fills some of these gaps. The BADIL Resource Center for Palestinian Residency and Refugee Rights published a critical analysis of UNHCR revised interpretation of the 1951 Refugee Convention.