Article 38 of the Statute of the International Court of Justice (ICJ) – annexed to the Charter of the United Nations – lists the following as sources of international law:

  • International conventions;
  • Customary international law;
  • General principles of law;
  • Judicial decisions (or jurisprudence), and the teachings of the most highly qualified legal scholars (publicists) of the various nations.

Since IML is part of international law, the sources of international law are also the sources of IML (Chetail, 2012: 56). International conventions and customary law are considered the primary sources; general principles and jurisprudence are considered subsidiary.

To Go Further
International Conventions (treaties)

International conventions are legally binding agreements among States, or among States and international organizations. Their aim is to establish rights and obligations under international law. Other terms such as “treaties”, “agreements”, “covenants”, “statutes”, and “protocols” are also commonly used. Once the terms of the treaty are agreed, the States involved will sign the treaty. By signing a treaty, a State expresses the intention to comply with the treaty. However, this expression of intent in itself is not binding. Once signed, each State will further process the treaty according to its own national procedures and law. Often, parliamentary approval is required. After approval has been granted under a State’s own internal procedures, the State will notify the other parties that it consents to be bound by the treaty. This is called ratification. Once it has been ratified, the treaty is legally binding on the State.

A specific branch of international law, called law of the treaties, deals with how treaties come into force and are administered. The main rules are codified in the Vienna Convention on the Law of Treaties. The Convention allows for States to make reservations to treaties, which means that they are not bound by the specific treaty provision(s) to which they made the reservation(s).

Customary international law

For a custom to become a norm in international law, and therefore customary international law, two elements are required. The first element is objective: States’ practice. That is, there must be widespread, consistent and repeated practice (or lack of action) by the majority of States. The conduct of a State is demonstrated by, among others things, official statements, court decisions, domestic legislation, administrative regulation, constitutions, treaties and diplomatic practice. The second element is subjective: opinio juris. This means the belief (“opinio”) of a State that it is bound by law (“juris”) to either act or refrain from acting.

International customary norms bind all States, including those that have not contributed to the development of the norm and regardless of treaty ratification. However, a State does not become bound by the norm if it shows consistent and persistent objection to it.

There are also a few norms under international law that are absolute. Called jus cogens, they are so fundamental that they are binding to all States, and no derogation or exemption is allowed. For example, the principle of non-refoulement, and the prohibition of torture, slavery, racial discrimination and genocide are considered jus cogens.

Example
The principle of non-refoulement

Protection against refoulement is a customary international norm with jus cogens status under international migration law (IML). That is, under no circumstances may a person (regardless of their legal status) be expelled or returned to a territory when there are substantial grounds to believe that there is a real risk that they will face persecution or irreparable harm to their person upon return. This applies to everyone, including migrants and regardless of status.

Examples of such risks of irreparable harm include:

  • Torture and cruel, inhumane or degrading treatment or punishment and other risks to life;
  • Flagrant denial of the right to a fair trial;
  • Violations to liberty of the person;
  • Serious forms of sexual and gender-based violence;
  • The death penalty or being placed on death row;
  • Female genital mutilation;
  • Prolonged solitary confinement;
  • Severe violations of economic, social and cultural rights (amounting to violation of the right to life or freedom from torture, degrading living conditions, complete lack of medical treatment, or mental illness).

The principle of non-refoulement is non-derogable; that is, it cannot be suspended or limited under any circumstances. It is established under international human rights law, international refugee law, international humanitarian law, transnational criminal law, and law of the sea (further details on the Protection against refoulement in Chapter 1.3.1 Human rights of migrants: An overview).

Other sources of law
General principles of law and jurisprudence

The third source of international law are those general principles of law common to major legal systems in the world and generally accepted as being binding at the international level (Robertson, 2002: 92). For a general principle of law to exist, it must be generally recognized by States. These principles derive from national legal systems and/or are formed within the international legal system. Examples include the principle of non-retroactivity of criminal law, due process guarantees, minimum standards of treatment, and so on. Many of them are already reflected in various treaties and/or customary international law.

The fourth source are judicial decisions (or jurisprudence). In a strict sense, international courts are not bound by judicial precedents. However, in practice, international and regional courts strive to follow previous judgements, in order to add some certainty to the process of judicial decision-making (Shaw, 1997: 86). As such, they have largely contributed to the development of IML. One clear example is the jurisprudence of the European Court of Human Rights, which has played a crucial role in interpreting the rights and obligations of States parties to the European Convention on Human Rights towards migrants (further details in Regional systems relevant to IML  in this chapter).

Example
Example of regional jurisprudence

In the case Bah v. United Kingdom, the complainant argued she and her son were victims of discrimination because of their immigration status. When assessing this case, the European Court of Human Rights (ECtHR) interpreted Article 14 of the European Convention on Human Rights, on the prohibition of discrimination, in relation to immigration status. Article 14 states that “The enjoyment of the rights and freedoms set forth in this Convention shall be secured without discrimination on any ground such as sex, race, colour, language, religion, political or other opinion, national or social origin, association with a national minority, property, birth or other status” [emphasis added]. The court held that immigration status can be considered “other status” for the purposes of article 14.

Source

European Court of Human Rights (ECtHR), Bah v. United Kingdom, 2011.

Soft law

Soft law is established in instruments such as “declarations”, “recommendations”, “plans of action”, “guidelines”, and “global compacts”. Although not a binding source of law, it helps to develop shared conduct among States and international organizations. Soft law generally provides a policy framework of cooperation in line with both States’ sovereignty and international law. Soft law serves as a tool that facilitates, at the policy and practice level, the operationalization of international law norms (hard law) that States have committed to (through treaty ratifications, as well as under customary international law and the principle of good faith that applies to all States). For example, in the field of IML, an important soft law instrument is the 2018 Global Compact for Safe, Orderly and Regular Migration.

Over time, soft law instruments or their content can become customary international law, or even serve as a stepping stone for the adoption of treaties. For example, the 1948 Universal Declaration of Human Rights was a stepping stone to the 1966 Covenants.

The resolutions of the General Assembly of the United Nations are an example of soft law. These, though not legally binding, indicate what States consider as right or wrong in international relations. Under international human rights law,  the considerations by the human rights treaty bodies of State party reports, individual communications and general comments provide an authoritative interpretation of the specific treaty they monitor. As well, the reports and statements of the human rights special procedure mechanisms help to determine obligations and rights under international human rights law.

Example
The revised deliberation no. 5 on deprivation of liberty of migrants, by the United Nations Working Group on Arbitrary Detention

In 2017, the United Nations Working Group on Arbitrary Detention revised its earlier Deliberation no. 5 on deprivation of liberty of migrants. The revised deliberation was based on the working group’s existing practice with regard to the detention of migrants, together with new developments in its own jurisprudence and in international law. That is, the deliberation represents the existing decisions of the working group, and compiles rules concerning detention.

The deliberation establishes that migrants and asylum seekers, regardless of their citizenship, nationality or migratory status, are entitled to the right to personal liberty, as it “is fundamental and extends to all persons at all times and circumstances”. There is no exemption from the prohibition of arbitrary detention: the deliberation notes that arbitrary detention can never be justified “including for any reason related to national emergency, maintaining public security or the large movements of immigrants or asylum seekers.” The deliberation also establishes that criminalizing irregular entry and stay in a country by migrants will “always exceed the legitimate interests of States in protecting their territories and regulating irregular migration flows.” In other words, irregular migration should not be criminalized. The deliberation explicitly prohibits the deprivation of liberty of children, regardless of whether they are asylum seekers, refugees, stateless persons or migrants. This is the case whether they are travelling unaccompanied or have been separated from their families. The deliberation also clarifies that detaining migrants during immigration procedures “must be justified as reasonable, necessary and proportionate in the light of the circumstances specific to the individual case”. Such detention is only allowable when it is for the shortest period of time, when it is not punitive in nature and when it is periodically reviewed as it extends over time. Finally, it establishes that detention should be an exceptional measure and that alternatives to detention are to be sought to ensure this.

Source

United Nations Working Group on Arbitrary Detention, 2018: 31–37.

Key messages
  • The principal sources of international migration law are treaties and customary international law.
  • Customary international law is binding on States without ratification (for example, laws prohibiting torture and refoulement). Other international legal instruments are only binding with ratification. However, signature without ratification obliges States to not act counter to the spirit of the signed instrument.
  • Other relevant sources of IML include general principles of law, which are overall accepted in major legal systems and recognized as binding internationally, and soft law. While non-binding, soft law plays an important role in developing shared conduct among States and international organizations. It can also inspire hard law instruments, and at the policy and practice level it supports putting hard law into use.
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