The Practical Guide to Humanitarian Law

« Calling things by the wrong name adds to the affliction of the world. » Albert Camus.

International Law

Law is the set of rules that organizes the lives of individuals in a society. Each society thus gives itself the means to organize its collective life and regulate its relations with other communities in a harmonious way, following preestablished “rules of the game,” known to all. Law has both a normative role—to establish the standards of behavior—and a judicial one—to ensure the means to enforce respect for the rules.

In a system of law, the victim does not procure justice for him- or herself. The community condemns failures to respect the established public or social order and is in charge of compensating the victim.

  • In a national society, the principle of the “social contract” ( contrat social ), which inherently ties individuals to society, reflects the will of individuals to be governed by collective rules. Some theorists refer to individuals’ willingness to be part of a group and share its rules.
  • In international society, States are prevailing actors. They agree on covenants or conventions. Each State remains sovereign but may choose to limit its own sovereignty by making commitments, through such conventions, that restrict its freedom of action in certain domains according to its domestic law.

Thus, international law is the set of rules adopted by States to govern relations either among themselves (public international law) or between individuals or legal entities of different nationalities (private international law). There exist several domestic legal systems that may be grouped according to their characteristics. Some are influenced by Continental tradition (civil law); others by common law; others are based on religious principles—in particular Islamic law—while some are influenced by ideologies such as communism. In fact, international law is a compromise between all of these above-mentioned sources, trends, and traditions. International law is the expression of rules shared by all States; these rules allow States to regulate their relationships, share minimum common values, and protect some international public order ( ordre publique ), security, and common interest. The structures and functioning of existing international tribunals also illustrate the search for a fair representation of all the existing legal systems, while setting up common rules and principles.

Human rightsInternational humanitarian lawNatural law, religious law and positive law


National and international law have three different sources:

  • Written texts: These are drafted and adopted by legitimate authorities responsible for enforcing the rule of law. In domestic law they have different names, such as statutes, regulations, ordinances, or decrees. In some countries these texts may include religious writings. In international law, these rules are usually set forth in international conventions.
  • Judicial precedents ( stare decisis*):* This encompasses the judgments rendered by legally established courts that apply and interpret existing legal rules for each individual case. International tribunals contribute to the creation of an international body of jurisprudence.
  • Custom: This is a general and consistent practice accepted as law. Not all rules are written, and certain societies function mainly on the basis of customary law, which is defended in litigious cases before the courts and then becomes case law. International law leaves a great deal of room for customary law, basing itself on the repeated and accepted behavior of States ( opinio juris ).

International actors therefore have a great responsibility in defending international law and ensuring its evolution since, if a rule is not upheld in practice, it is weakened and may even disappear. On the other hand, if the behavior of international actors is regular and coherent, it contributes to the establishment of new standards and laws. International law gives NGOs a right of initiative in humanitarian matters, which gives them a share of the responsibility for the evolution of custom in this field.

There are different legal systems in the world. Even within one system, such as that of common law, the procedure may vary. The main differences may be reflected in the sources of law on which the judiciary bases itself, the hierarchy of norms that must be respected, the rights given to each party to a dispute, and the procedure followed in each case.

The entry on ▸ Hierarchy of norms provides some examples of the different legal sources and their status as positive law—for instance, the different force of law that judicial precedents have in different systems. There are, however, certain peremptory norms of international law ( jus cogens norms, explained later) that are considered binding on all States. Furthermore, international conventions, and particularly international courts, have incorporated various elements into their structure to take the different legal systems into account. Conventions, for instance, try to be of universal appeal and, once ratified, must be integrated into the domestic legal system.

In the case of international tribunals, it is all the more important to find a solution to any contradictions between the legal systems so that they, too, can strive for universal adherence. At the very least, most international courts posit that their members must represent “the principal legal systems of the world,” as are enshrined in the statutes of the ▸ International Court of Justice , the International Criminal Tribunals for the former Yugoslavia and Rwanda, and the International Criminal Court. In the case of recently established tribunals, in particular the ▸ International Criminal Court , innovative efforts have been made to combine different legal systems of the world more concretely. The structure of the ICC and some of the rights accorded to victims, for instance, reflect a blend of systems—in particular, those of common law and civil law.

The entry on ▸ International Criminal Tribunals explains some of the differences between these two systems—namely, in terms of the approach to criminal substantive law, trial procedures, rights of the victims and accused—under the section “Legal Basis of the Tribunals: International Law, Civil Law, and Common Law.”

See also ▸ Customary international lawInternational conventionsRight of humanitarian initiative.

Hierarchy of Norms

The many different rules and regulations that exist have a varying force or status of law, depending on the legal body and procedure by which they were adopted. In each situation, it is therefore important to compare the different applicable laws according to the official hierarchy of norms. If there is a contradiction between two principles of law, the one that has a higher legal authority prevails.

Nonetheless, certain rules—including unwritten ones—must prevail in all circumstances. Historically, this fact was reflected in the tension between the proponents of “natural law” (a right based on moral or religious values) on the one hand and proponents of “positive law” (a written right that represents the free will of the majority of States (for international law) or citizens (for domestic law) on the other. Today, most States and legal systems recognize the existence of peremptory norms, known as jus cogens .

Hierarchy of normsNatural law, religious law and positive law

Jus Cogens

The notion of jus cogens was firmly established by the 1969 Vienna Convention on the Law of Treaties, which reaffirms the existence of certain norms of international law that are “accepted and recognized by the international community of states, as a whole, as a norm from which no derogation is permitted” (Art. 53). These norms are binding on all States, without exception, and any convention or other international text that infringes on or violates these norms is void to the extent of the inconsistency. States have agreed that jus cogens norms prohibit acts such as genocide, slavery, and aggression. However, additional elements of this law have yet to be defined. That is one of the International Court of Justice’s roles.

International human rights and humanitarian law conventions enumerate the rights and obligations from which no State can derogate, under any circumstance. These fundamental guarantees, or “non-derogable rights,” represent the minimum standard of protection for individuals and are peremptory norms of international law.

Fundamental guarantees


Laws may be interpreted according to certain well-defined principles. These include:

  • the spirit of the law (meaning the intent of the legislator or drafter),
  • the coherence between the interpretation of a law and its objectives, and
  • good faith.

Each rule of law is subject to different interpretations.

In the context of international law, it may be that no court exists that can rule on such questions of law. NGOs must monitor the implementation of international human rights and humanitarian law so as to ensure that States do not interpret them in unilateral or abusive ways. The Vienna Convention on the Law of Treaties set up the rules according to which international conventions must be interpreted. The International Court of Justice also has a role to play when judging cases in which States disagree on the interpretation of an international convention. Indeed, the ICJ has recently recalled that

according to customary international law as expressed in Article 31 of the Vienna Convention on the Law of Treaties of 23 May 1969, a treaty must be interpreted in good faith in accordance with the ordinary meaning to be given to its terms in their context and in the light of its object and purpose. Article 32 provides that: “Recourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to confirm the meaning resulting from the application of article 31, or to determine the meaning when the interpretation according to article 31 . . . leaves the meaning ambiguous or obscure; or . . . leads to a result which is manifestly obscure or unreasonable. ( Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory , Advisory Opinion, ICJ Reports 2004, p. 136, para. 94—infra Jurisprudence)

International conventions


International law applies in a different manner on the territory of States concerned. Some clauses are precise enough to be “self-executing,” and therefore an individual can invoke these norms directly before domestic courts. Many provisions, on the other hand, are “non-self-executing,” meaning that the rules or procedures must be incorporated into national legislation before an individual may have recourse to such laws. This is particularly the case for issues of international criminal law, and even more so with regard to the prosecution of war crimes and crimes against humanity.


Courts impose sanctions for breaches of the law. The aim of the sanction is to reestablish public order and to compensate victims.

In the international order, the role of the judiciary was very limited for a long time. Since the end of the Cold War, however, it has shown important development. Two permanent international tribunals currently exist. The International Court of Justice is responsible for prosecuting States that violate their international obligations. However, it has no jurisdiction over criminal matters, cannot judge individuals, and can only judge States with their consent. The Statute of the International Criminal Court was adopted in Rome in 1998 and entered into force on 1 July 2002. Its mandate is to prosecute those responsible for war crimes, crimes against humanity, and genocide. There are also two ad hoc International Criminals Tribunals responsible for prosecuting those who committed crimes in the former Yugoslavia and Rwanda (respectively established by the UN Security Council in 1993 and 1994).

Besides being sanctioned by judicial mechanisms, specific behavior that threatens international peace and security may be sanctioned by the UN Security Council. Chapter VII of the UN Charter foresees the possibility of imposing diplomatic, economic, and military sanctions on States or non-states actors (individuals, political parties, belligerents). These measures include embargoes, restricting or interrupting economic or diplomatic relations, freezing of assets, and bans on travel, as well as recourse to international armed force.

International Criminal CourtInternational Criminal TribunalsUniversal jurisdiction

  • At the regional level, three courts may judge States violating human rights: the European Court of Human Rights, the Inter-American Court of Human Rights, and the African Court of Human and People’s Rights (which will merge with the African Court of Justice when the Protocol on the Statute of the African Court of Justice and Human Rights, adopted in 2008, enters into force).
  • At the national level, those who committed serious breaches of humanitarian law (war crimes, crimes against humanity) may—under certain circumstances—be prosecuted by any domestic court, according to the universal jurisdiction principle. There are also non-judicial bodies to which individuals or other entities may have recourse; these are explained in the entries on ▸ Human rightsIndividual recourse .


  • The right of victims of human rights violations to receive reparation is recent in international law. The statute of the International Criminal Court (Art. 75) adopted in July 1998 provides the possibility of reparation for victims of genocide, war crimes, and crimes against humanity.
  • For many years, the only mechanisms available to such victims and their families were the rare judicial decisions from domestic court, ad hoc procedures such as Truth and Reconciliation Committees, or funds created within the UN.
  • There are two particular funds created by the UN General Assembly. The first is the United Nations Voluntary Fund for Victims of Torture, created in 1982; the second is the Voluntary Fund for Victims of Contemporary Forms of Slavery, created in 1991.
  • At the regional level, the European, Inter-American, and African Courts may provide appropriate reparation to victims of violations of the European, Inter-American, and African Conventions on Human Rights (Art. 13 of the European Convention, Arts. 25 and 63 of the Inter-American Convention, Art. 7 of the African Charter on Human and People’s Rights, Arts. 28.h and 45 of the 2008 Protocol on the Statute of the African Court of Justice and Human Rights, and Art. 3.2 of the 2005 Supplementary Protocol to the ECOWAS Court of Justice).

Customary international lawAfrican Commission and Courts for Human RightsEmbargoEuropeanCourt of Human RightsHierarchy of normsHuman rightsIndividual recourse;Inter-American Court of, and Commission on, Human RightsInternational conventionsInternational Court of JusticeInternational Criminal CourtInternational Criminal TribunalsNatural law, religious law and positive lawPenal sanctions in humanitarian lawReparation (Compensation)Sanctions (diplomatic, economic, or military)Security Council of the UNSoft lawUniversal jurisdictionWar crimes/Crimes against humanity


In several cases, the International Court of Justice (ICJ) recalled the principles and criteria of interpretation of international law as they appear in customary law and in the Vienna Convention on the Law of Treaties. The ICJ recalled that a text shall be interpreted in good faith and according to the intention of its drafters and insisted on the fact that the interpretation made by States cannot lead to a result that is “manifestly obscure or unreasonable.” See Oil Platforms ( Islamic Republic of Iran v. United States of America ), Preliminary Objection, Judgment, ICJ Reports 1996 (II), p. 812, para. 23; Kasikili/Sedudu Island ( Botswana v. Namibia ), Judgment, ICJ Reports 1999 (II), p. 1059, para. 18; Sovereignty over Palau Ligitan and Palau Sipadan ( Indonesia v. Malaysia ), Judgment, ICJ Reports 2002, p. 645, para. 37; and Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory , Advisory Opinion, ICJ Reports 2004, p. 136, para. 94.

For Additional Information: Bothe, Michael, Carl Bruch, Jordan Diamond, and David Jensen. “International Law Protecting the Environment during Armed Conflict: Gaps and Opportunities.” International Review of the Red Cros s 879 (September 2010): 569–92.

Brownlie, Ian. Principles of Public International Law . Oxford: Oxford University Press, 2003.

Carter, Barry E., and Philippe R. Trimble. International Law . Boulder, CO: Aspen, 1999.

Higgins, Rosalyn. Problems and Process: International Law and How We Use It . Oxford: Clarendon Press, 1994.

Shaw, Malcolm. International Law . 4th ed. Cambridge: Cambridge University Press, 1997.

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