International law
In international law, opinio juris is the subjective element used to judge whether the practice of a state is due to a belief that it is legally obligated to do a particular act. [1] [2] When opinio juris exists and is consistent with nearly all state practice, customary international law emerges. Opinio juris essentially means that states must act in compliance with the norm not merely out of convenience, habit, coincidence, or political expediency, but rather out of a sense of legal obligation. [3]
Article 38(1)(b) of the Statute of the International Court of Justice accepts "international custom" as a source of law, but only where this custom is 1) "evidence of a general practice," (the objective component) (2) "accepted as law." (the opinio juris or subjective component) [4] Thus, for example, while it may be observed that heads of state virtually always shake hands when they first meet, it is highly unlikely that they do so because they believe that a rule of international law requires it. On the other hand, a state would almost certainly expect some form of legal repercussions if it were to prosecute a foreign ambassador without the consent of his or her home state, and in this sense opinio juris does exist for the international law rule of diplomatic immunity.
Because opinio juris refers to the psychological state of the state actor – asking why the state behaved as it did – it can be difficult to identify and to prove. In practice, a variety of sources tend to be used to demonstrate the existence of opinio juris, including evidence such as diplomatic correspondence, press releases and other government statements of policy, opinions of legal advisers, official manuals on legal questions, legislation, national and international judicial decisions, legal briefs endorsed by the state, a pattern of treaties ratified by the state that all include the same obligation(s), resolutions and declarations by the United Nations, and other sources.
In the Paquete Habana case (decided by the United States Supreme Court in 1900 on the question of whether small coastal fishing boats are immune from capture during wartime under customary international law), evidence of opinio juris included medieval English royal ordinances, agreements between European nations, orders issued to the U.S. Navy in earlier conflicts, and the opinions of legal treatise writers. Finally, the context, circumstances, and manner in which the state practice is carried out can also be used to infer the existence of opinio juris.
As the ICJ stated in the North Sea Continental Shelf cases of 1969, "Not only must the acts concerned amount to a settled practice, but they must also be such, or be carried out in such a way, as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it." [5] Nonetheless, a state's motives can change over time, and that it is not necessary that opinio juris be a significant impetus for each instance of action. As Judge Lachs wrote in a dissenting opinion in the North Sea Continental Shelf cases, "At successive stages in the development of the [customary] rule the motives which have prompted States to accept it have varied from case to case. It could not be otherwise. At all events, to postulate that all States, even those which initiate a given practice, believe themselves to be acting under a legal obligation is to resort to a fiction, and in fact to deny the possibility of developing such rules." [6]
As difficult as it can be to prove why an actor did act in a certain way, it is exponentially more difficult to prove why it did not act. For this reason, the necessity of demonstrating that a behavior was prompted by a sense of legal obligation makes it particularly difficult for customary international law to develop around the prohibition of a practice. One important case in the development of modern customary international law theory is the Lotus case, in which France attempted to protest Turkey's assertion of criminal jurisdiction over a French citizen for acts committed on the high seas (outside of Turkey's territory). France presented a number of historical examples to demonstrate that the state of nationality or the state whose flag the ship had flown had exclusive jurisdiction in cases such as this. However, the Permanent Court of International Justice (a precursor to the ICJ) declared that the evidence showed merely that "States had often, in practice, abstained from instituting criminal proceedings, and not that they recognized themselves as being obliged to do so; for only if such abstention were based on their being conscious of having a duty to abstain would it be possible to speak of an international custom." [7]
This reasoning was cited approvingly in the North Sea Continental Shelf cases, which similarly declined to find the existence of customary law regarding the proper method to delimit territorial claims to the continental shelf extending from the coastline of states bordering the North Sea. [8] The ICJ also declined to find evidence of customary international law in an opinion on the legality of the use or threat of nuclear weapons, despite what some argued to be uniform state practice.
As in the North Sea Continental Shelf cases, in the advisory opinion on the Legality of the Threat or Use of Nuclear Weapons it found that the mere fact that no state had used nuclear weapons against another state since World War II did not reflect opinio juris. Some states had pointed out that a series of U.N. resolutions had been issued "that deal with nuclear weapons and that affirm, with consistent regularity, the illegality of nuclear weapons," and argued that this signified "the existence of a rule of international customary law which prohibits recourse to those weapons." [9] Nonetheless, the ICJ wrote that states possessing nuclear weapons had almost always objected to these resolutions, which strongly suggests that those states did not believe that a customary law prohibiting their use existed. Moreover, it wrote that the non-use of nuclear weapons could actually provide evidence of their "use" as a deterrent force. [10]
This logical framework makes sense for existing norms of customary international law, but it becomes problematic in the context of new or emerging customary rules. If a practice is not currently governed by customary international law, then it is illogical to inquire into a state's beliefs about the legality of engaging in or abstaining from that practice, i.e., to ask whether it believed that its practice was in compliance with a law that does not yet exist.
This paradox may be resolved to some extent by the idea of "crystallization" of customary international law, in which practice and legal obligation evolve jointly and eventually ripen into law. Under one model, this process occurs in three stages: first, some States engage in a given practice for reasons other than a sense of legal obligation (e.g. political expediency, economic gain, courtesy, etc.); next, States reinforce the practice by engaging in it or making claims based upon it, creating loops of reciprocity and reliance based on expectations that the practice will continue; finally, as these relationships expand in number and complexity, they eventually harden into a general rule. In this final stage, as more States become aware of the conduct and actively participate or at least passively acquiesce to the practice, the States' actions begin to be undergirded by a belief that they are complying with an emerging customary rule.
The International Court of Justice, also called the World Court, is one of the six principal organs of the United Nations (UN). It settles disputes between states in accordance with international law and gives advisory opinions on international legal issues. The ICJ is the only international court that adjudicates general disputes between countries, with its rulings and opinions serving as primary sources of international law.
The Republic of Nicaragua v. The United States of America (1986) was a case where the International Court of Justice (ICJ) held that the U.S. had violated international law by supporting the Contras in their rebellion against the Sandinistas and by mining Nicaragua's harbors. The case was decided in favor of Nicaragua and against the United States with the awarding of reparations to Nicaragua.
The United Nations Convention on the Law of the Sea (UNCLOS), also called the Law of the Sea Convention or the Law of the Sea Treaty, is an international agreement that establishes a legal framework for all marine and maritime activities. As of May 2023, 168 countries and the European Union are parties.
Legality of the Threat or Use of Nuclear Weapons[1996] ICJ 3 is a landmark international law case, where the International Court of Justice gave an advisory opinion stating that while the threat or use of nuclear weapons would generally be contrary to international humanitarian law, it cannot be concluded whether or not such a threat or use of nuclear weapons would be lawful in extreme circumstances where the very survival of a state would be at stake. The Court held that there is no source of international law that explicitly authorises or prohibits the threat or use of nuclear weapons but such threat or use must be in conformity with the UN Charter and principles of international humanitarian law. The Court also concluded that there was a general obligation to pursue nuclear disarmament.
Customary international law is an aspect of international law involving the principle of custom. Along with general principles of law and treaties, custom is considered by the International Court of Justice, jurists, the United Nations, and its member states to be among the primary sources of international law.
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.
International law, also known as "law of nations", refers to the body of rules which regulate the conduct of sovereign states in their relations with one another. Sources of international law include treaties, international customs, general widely recognized principles of law, the decisions of national and lower courts, and scholarly writings. They are the materials and processes out of which the rules and principles regulating the international community are developed. They have been influenced by a range of political and legal theories.
The use of force by states is controlled by both customary international law and by treaty law. The UN Charter reads in article 2(4):
All members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations.
The International Court of Justice has jurisdiction in two types of cases: contentious cases between states in which the court produces binding rulings between states that agree, or have previously agreed, to submit to the ruling of the court; and advisory opinions, which provide reasoned, but non-binding, rulings on properly submitted questions of international law, usually at the request of the United Nations General Assembly. Advisory opinions do not have to concern particular controversies between states, though they often do.
Sir Christopher John Greenwood is Master of Magdalene College, Cambridge and a former British judge at the International Court of Justice. Prior to his election, he was professor of international law at the London School of Economics and a barrister who regularly appeared as counsel before the International Court of Justice, the European Court of Human Rights, the English courts, and other tribunals.
Stephen Myron Schwebel, is an American jurist and international judge, counsel and arbitrator. He previously served as judge of the World Bank Administrative Tribunal (2010–2017), as a member of the U.S. National Group at the Permanent Court of Arbitration, as president of the International Monetary Fund Administrative Tribunal (1993–2010), as president of the International Court of Justice (1997–2000), as vice president of the International Court of Justice (1994–1997), and as Judge of the International Court of Justice (1981–2000). Prior to his tenure on the ICJ, Schwebel served as deputy legal adviser to the U.S. Department of State (1974–1981) and as assistant legal adviser to the U.S. Department of State (1961–1967). He also served as a professor of law at Harvard Law School (1959–1961) and Johns Hopkins University (1967–1981). Schwebel is noted for his expansive opinions in momentous cases such as Legality of the Threat or Use of Nuclear Weapons, Military and Paramilitary Activities in and Against Nicaragua and Oil Platforms .
War can heavily damage the environment, and warring countries often place operational requirements ahead of environmental concerns for the duration of the war. Some international law is designed to limit this environmental harm.
International law is the set of rules, norms, and standards generally recognized as binding between states. It establishes norms for states across a broad range of domains, including war and diplomacy, economic relations, and human rights. International law differs from state-based domestic legal systems in primarily, though not exclusively, applicable to states, rather than to individuals, and operates largely through consent, since there is no universally accepted authority to enforce it upon sovereign states. States may choose to not abide by international law, and even to breach a treaty but such violations, particularly of peremptory norms, can be met with disapproval by others and in some cases coercive action ranging from diplomatic and economic sanctions to war.
Distinction is a principle under international humanitarian law governing the legal use of force in an armed conflict, whereby belligerents must distinguish between combatants and protected civilians. Combatant in this instance means persons entitled to directly participate in hostilities and thus are not afforded immunity from being directly targeted in situations of armed conflict. Protected civilian in this instance means civilians who are enemy nationals or neutral citizens outside of the territory of a belligerent power.
The Martens Clause is an early international law concept first introduced into the preamble of the 1899 Hague Convention II – Laws and Customs of War on Land. There are differing interpretations of its significance on modern international law, with some scholars simply treating the clause as a reminder international customary law still applies after a treaty is ratified while others take a more expansive approach where the clause provides that because international treaties cannot be all encompassing, states cannot use that as a justification for an action.
Political leaders of the US and UK who led the arguments which resulted in the invasion of Iraq have claimed that the war was legal. However, legal experts, including the chairman of the Iraq Inquiry, John Chilcot, who led an investigation with hearings from 24 November 2009 to 2 February 2011, concluded that the process of identifying the legal basis for the invasion of Iraq was unsatisfactory and that the actions of the US and the UK have undermined the authority of the United Nations.
The Corfu Channel case was the first public international law case heard before the International Court of Justice (ICJ) between 1947 and 1949, concerning state responsibility for damages at sea, as well as the doctrine of innocent passage. A contentious case, it was the first of any type heard by the ICJ after its establishment in 1945.
Denmark/Federal Republic of Germany/Netherlands [1969] ICJ 1 were a series of disputes that came to the International Court of Justice in 1969. They involved agreements among Denmark, Germany, and the Netherlands regarding the "delimitation" of areas—rich in oil and gas—of the continental shelf in the North Sea.
Customary international humanitarian law is a body of unwritten rules of public international law, which govern conduct during armed conflict.
