International law constitutes the foundational legal framework governing relations among states, international organizations, and, increasingly, individuals and non-state actors in the global arena. Rooted in centuries of customary practice, multilateral treaties, and judicial decisions, international law seeks to promote peace, security, justice, and human dignity across borders. It encompasses a broad spectrum of subfields, including the law of the sea, international environmental law, international trade law, and international human rights law. Among its most critical branches is international humanitarian law (IHL)—also known as the law of armed conflict—which specifically regulates the conduct of hostilities and the protection of persons who are not, or are no longer, participating in hostilities during times of war.
While international law generally applies in peacetime, IHL is triggered exclusively in situations of armed conflict, whether international or non-international in character. Its core purpose is humanitarian: to limit the effects of war by safeguarding civilians, wounded combatants, prisoners of war, and other vulnerable groups, and by restricting the means and methods of warfare. Codified primarily in the Geneva Conventions of 1949 and their Additional Protocols, as well as in customary international law, IHL operates alongside international human rights law (IHRL), with which it overlaps but also differs in scope, applicability, and legal sources. Notably, whereas IHRL remains applicable at all times—though certain rights may be subject to lawful derogation during emergencies—IHL applies only during armed conflict and takes precedence as the lex specialis in matters concerning the conduct of hostilities and the treatment of protected persons.
The interplay between these legal regimes reflects the broader evolution of international law from a state-centric system toward one that increasingly recognizes the rights and responsibilities of individuals. This shift is evident in the establishment of international criminal tribunals, the principle of universal jurisdiction, and the growing emphasis on state accountability for violations such as war crimes, crimes against humanity, and torture. Understanding the structure, sources, and normative foundations of both general international law and its specialized branch—international humanitarian law—is essential for analyzing contemporary global challenges, from armed conflicts and occupation to refugee protection and post-conflict justice. This article provides a concise overview of these legal frameworks, their historical development, key principles, and their role in upholding human dignity in both peace and war.
For students of law, politics, and global affairs, few subjects are as foundational—and as frequently misunderstood—as international law. Often perceived as weak or unenforceable, international law in fact constitutes a sophisticated legal order that shapes state behavior, protects individual rights, and regulates everything from diplomatic relations to armed conflict. Within this broader system exist specialized branches, notably international humanitarian law (IHL) and international human rights law (IHRL), each with distinct origins, functions, and legal sources. This article provides a structured overview of the architecture of international law, highlighting how IHL and IHRL operate within—and sometimes intersect with—this global legal framework. By clarifying their meaning, historical development, and normative underpinnings, the article aims to equip students with a coherent conceptual map for navigating contemporary legal and ethical challenges in world affairs.
International Law #
Meaning, Structure, and Sources #
International law (IL) is the body of rules, norms, and standards that govern the conduct of sovereign states and other subjects of international law—including international organizations, certain non-state actors, and, in specific contexts, individuals. Unlike domestic legal systems, which feature centralized legislatures, courts, and enforcement mechanisms, international law operates in a decentralized, consensual environment often described as anarchical—not in the sense of chaos, but in the absence of a supreme authority above states.
Sources of International Law #
Article 38(1) of the Statute of the International Court of Justice (ICJ) provides the classical formulation of the sources of international law:
- International treaties (conventions): Legally binding agreements between states (e.g., the UN Charter, the Geneva Conventions). Once ratified, treaties create obligations for the parties.
- Customary international law: Practices that are widespread among states (state practice) and carried out with a sense of legal obligation (opinio juris). Custom binds all states, unless they persistently object during its formation.
- General principles of law recognized by civilized nations: Foundational legal concepts common to major legal systems (e.g., good faith, equity, prohibition of abuse of rights).
- Judicial decisions and the teachings of the most highly qualified publicists: Subsidiary means for determining rules of law, not primary sources in themselves.
In addition to these formal sources, soft law—non-binding instruments such as declarations, resolutions, and guidelines—often plays a catalytic role in the development of new norms.
Normative Foundations #
International law is underpinned by core principles that reflect the post-World War II international order:
- Sovereign equality of states (UN Charter, Art. 2(1))
- Prohibition of the use of force (UN Charter, Art. 2(4))
- Self-determination of peoples
- Pacta sunt servanda (treaties must be performed in good faith)
- Responsibility for internationally wrongful acts
- Crucially, certain norms have attained the status of jus cogens—peremptory norms from which no derogation is permitted (e.g., prohibition of genocide, slavery, torture, and aggression). Violations of jus cogens norms entail obligations erga omnes (owed to the international community as a whole), enabling broader standing for enforcement.
International Humanitarian Law (IHL) #
(Law in Times of War)
IHL, also known as the law of armed conflict or law of war, is the branch of international law that seeks to limit the effects of armed conflict by protecting persons who are not participating in hostilities and by restricting the means and methods of warfare.
Historical Origins #
IHL traces its modern roots to the mid-19th century, particularly the 1864 Geneva Convention (initiated by Henry Dunant following the Battle of Solferino) and the Hague Conventions of 1899 and 1907, which regulated the conduct of warfare. The system was significantly expanded after World War II with the Four Geneva Conventions of 1949, later supplemented by Additional Protocols I and II (1977).
Scope and Applicability #
IHL applies only during armed conflict—whether:
International armed conflicts (IACs): Between two or more states (governed by Geneva Conventions I–IV and Additional Protocol I)
Non-international armed conflicts (NIACs): Between state forces and non-state armed groups, or among such groups (governed primarily by Common Article 3 of the Geneva Conventions and Additional Protocol II)
Unlike human rights law, IHL does not apply in peacetime. Its activation is factual: once a situation meets the threshold of armed conflict, IHL applies automatically, regardless of formal declarations.
Core Principles #
IHL is guided by several cardinal principles:
- Distinction: Parties must distinguish between combatants and civilians, and between military objectives and civilian objects.
- Proportionality: Attacks must not cause excessive civilian harm in relation to the anticipated military advantage.
- Necessity: Only the degree of force necessary to achieve a legitimate military objective is permitted.
- Humanity: Even in war, human suffering must be minimized; certain weapons and tactics (e.g., torture, perfidy, chemical weapons) are prohibited.
- IHL also grants specific protections to categories of persons: wounded and sick soldiers, prisoners of war, civilians in occupied territories, and humanitarian personnel.
International Human Rights Law (IHRL) #
(Law in All Circumstances)
IHRL comprises the body of international rules that protect the inherent dignity and fundamental freedoms of all human beings. It emerged prominently after World War II with the adoption of the Universal Declaration of Human Rights (1948) and was codified in binding treaties such as the International Covenant on Civil and Political Rights (ICCPR) and the International Covenant on Economic, Social and Cultural Rights (ICESCR) (both 1966).
Key Features #
- Universal application: IHRL applies at all times—to all individuals within a state’s territory or under its jurisdiction.
- Derogation permitted in emergencies: Certain rights (e.g., freedom of movement, right to assembly) may be temporarily suspended during public emergencies, but only if strictly required and non-discriminatory (ICCPR, Art. 4). Core rights—such as the prohibition of torture, slavery, and retroactive punishment—are non-derogable.
- Vertical obligation: States are primarily responsible for respecting, protecting, and fulfilling human rights.
Relationship with IHL #
During armed conflict, both IHL and IHRL apply concurrently. The ICJ affirmed this principle in its 2004 Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory advisory opinion. However, IHL operates as the lex specialis—the more specific law—governing issues directly related to the conduct of hostilities and treatment of protected persons. For example, the detention of combatants in an IAC is governed by IHL (Geneva Convention III), while the right to a fair trial for civilians may draw on both regimes.
Complementarity and Tensions #
While IHL and IHRL share the common goal of protecting human dignity, they differ in origin, scope, and function:
- IHL is exceptional—activated only in war, focused on regulating violence.
- IHRL is permanent—applicable in peace and war, focused on individual rights and state accountability.
Tensions can arise, particularly in non-international conflicts where IHL provides fewer procedural safeguards than IHRL. Yet, international jurisprudence increasingly emphasizes complementarity: using IHRL to fill gaps in IHL, especially in areas like due process and humane treatment.
Moreover, both bodies of law intersect with international criminal law, which holds individuals accountable for war crimes (under IHL), crimes against humanity, and genocide (under both IHL and IHRL).
Key Consideration #
International law is not a monolithic code but a dynamic, layered system that adapts to the complexities of global life. Its specialized branches—IHL and IHRL—reflect humanity’s dual commitment to regulating the brutality of war and safeguarding human dignity in all circumstances. Understanding the structure, sources, and normative logic of these legal regimes is essential not only for academic clarity but also for informed engagement with real-world crises—from armed occupations and refugee flows to accountability for torture and unlawful detention. As global challenges evolve, so too must our grasp of the legal frameworks designed to uphold justice, humanity, and peace in an interconnected world.
