Public International Law and IHL

International law: nature, sources, recognition

International law is law between sovereign equals, supplemented today by rules binding international organisations and, in human rights and humanitarian law, conferring protections on individuals. Its decentralised character explains both its strength and its limits: because states make the law that binds them, compliance is often high in routine matters such as diplomacy, trade, transport, and communications, where mutual benefit is clear; in high-stakes security matters, compliance depends more on power, alliances, and reputational cost. Theories of the subject reflect this tension. One tradition emphasises consent and sovereignty, treating obligation as flowing from agreement and practice. Another emphasises community and shared values, treating certain rules as binding regardless of individual consent because they protect humanity as a whole. A practical answer acknowledges both: most rules rest on consent and custom, while a small core of peremptory norms is treated as non-derogable.

The classic sources are treaties, customary practice accepted as law, general principles recognised by legal systems, and, as subsidiary means, judicial decisions and expert writings. Treaties bind parties that consent to them, and their interpretation follows the ordinary meaning of terms in context, in light of object and purpose, with regard to subsequent practice and relevant rules of international law. Custom requires two elements: general, consistent state practice and a belief that the practice is legally required. General principles fill gaps where treaty and custom are silent, drawing on ideas common to domestic systems such as good faith, estoppel, and responsibility for wrongful acts. The relationship with domestic law varies by constitutional system: in some systems international law is automatically part of domestic law, in others it requires incorporation by legislation, and in practice courts often interpret domestic law to avoid conflict with international obligations where the text allows. State responsibility follows when a state commits an internationally wrongful act attributable to it, triggering duties of cessation, non-repetition, and reparation.

Recognition is the process by which existing states accept a new state or government as a member of the international community. Theories divide between the declaratory view, under which a state exists when it meets factual criteria of territory, population, government, and capacity to enter relations, and recognition merely acknowledges that fact, and the constitutive view, under which recognition itself creates statehood. Modern practice leans declaratory for statehood while retaining political discretion for governments and for admission to organisations. Recognition has practical consequences for treaty relations, diplomatic immunity, access to courts, and membership, but non-recognition does not erase facts on the ground, and duties under humanitarian and human rights law may apply regardless of recognition disputes. Succession adds a further layer: when states merge, divide, or emerge, questions arise about continuity of treaties, debts, property, and nationality, resolved by agreement, practice, and principles protecting acquired rights and the stability of boundaries.

Nationality, refugees, extradition and asylum

Nationality is the legal bond between a person and a state, conferring rights such as diplomatic protection and duties such as allegiance, and grounding the state's jurisdiction over its nationals abroad. States largely determine their own nationality laws, subject to limits against arbitrary deprivation and statelessness, because nationality determines where a person belongs in a world organised by states. Dual nationality creates overlapping claims, resolved by principles of effective nationality and by treaties, while statelessness leaves a person without a protecting state and is therefore treated as a harm to be prevented through safeguards at birth, on state succession, and on loss or renunciation. Nationality must be distinguished from residence, domicile, and citizenship in domestic law: a person may live somewhere without that state's nationality, and nationality alone does not settle every question of tax, voting, or social entitlement, which domestic law regulates separately.

Refugee law protects persons who cannot safely return home because of a well-founded fear of persecution on protected grounds, including race, religion, nationality, membership of a particular social group, and political opinion. The core protection is non-refoulement: a person must not be returned to a place where life or freedom would be threatened on such grounds. Refugee status is declaratory in the sense that a person is a refugee when the criteria are met, even before formal determination, though states operate procedures to recognise status and grant associated rights to work, education, and movement. Asylum is the protection a state grants within its territory, an exercise of sovereignty that is also constrained by human rights law against return to torture or inhuman treatment. Extradition is the surrender of a person accused or convicted of a crime to another state under treaty or law, subject to safeguards such as double criminality, specialty, refusal for political offences, and refusal where a fair trial or protection from persecution cannot be assured. Together these doctrines show sovereignty in negotiation: states control entry and surrender, but not without regard to persecution, torture, and fair process.

United Nations, disputes and WTO

The United Nations is founded on sovereign equality, non-intervention in domestic jurisdiction except as the charter provides, peaceful settlement of disputes, and prohibition of the threat or use of force against territorial integrity or political independence, subject to self-defence and collective security action. Its principal organs divide labour: a general assembly deliberates and recommends, a security council bears primary responsibility for peace and security and can authorise binding measures, a secretariat administers, an economic and social council coordinates development and rights work, and a court adjudicates legal disputes between states that accept its jurisdiction. The security council's voting structure, including the veto of permanent members, makes it powerful when united and blocked when divided, which is why much peace work proceeds through assembly action, regional arrangements, peacekeeping with host consent, and diplomacy alongside formal enforcement.

Peaceful settlement is an obligation, not an option to be ignored: states must seek settlement by negotiation, enquiry, mediation, conciliation, arbitration, judicial settlement, resort to regional agencies, or other peaceful means of their choice. Negotiation remains the most common method, while mediation and conciliation add third-party assistance without binding outcomes, arbitration produces binding awards from tribunals chosen by the parties, and judicial settlement before the world court produces binding judgments on legal questions between consenting states. The world court also gives advisory opinions to authorised organs, which, though not binding as judgments, carry great authority. The trade system complements this security architecture with an economic one: its core principles are non-discrimination through most-favoured-nation treatment and national treatment, progressive liberalisation through negotiated commitments, transparency, and special treatment for developing members. Its dispute system moves from consultation through panel adjudication to appellate review and authorised retaliation where compliance fails, expressing a preference for rules over unilateral retaliation in trade conflict.

International humanitarian law

International humanitarian law applies in armed conflict, whether between states or, in its core protections, within a state, and it binds parties regardless of who started the conflict or who fights justly. Its purpose is to limit suffering: it protects persons who do not take part in hostilities and those who have ceased to take part, such as the wounded, sick, detained, and surrendered, and it restrains means and methods of warfare. The distinction principle requires parties to distinguish civilians and civilian objects from combatants and military objectives, directing attacks only at the latter. Proportionality prohibits attacks expected to cause incidental civilian harm excessive in relation to the concrete military advantage anticipated. Military necessity permits only measures actually necessary to achieve a legitimate military purpose, while humanity prohibits cruelty and unnecessary suffering. Precautions require feasible steps to verify targets, choose means that minimise civilian harm, and warn where circumstances permit.

Protected persons include civilians, medical personnel, humanitarian workers, prisoners of war, and other detainees, each with defined rights to humane treatment, medical care, communication with family, and fair process where penal proceedings follow. Torture, cruel and degrading treatment, hostage-taking, and summary execution are prohibited in all circumstances. Weapons and tactics are limited: weapons that cause superfluous injury or unnecessary suffering, that cannot distinguish between civilian and military targets, or that cause widespread, long-term environmental damage are restricted or prohibited, and new weapons must be reviewed for compliance before adoption. Grave breaches of humanitarian law entail individual criminal responsibility, prosecuted nationally or before international courts and tribunals, so humanitarian law is not merely aspirational. Its relation to human rights law is complementary: human rights law applies at all times but may be derogated from in emergency under conditions, while humanitarian law is the specialised law of armed conflict, and in conflict the two are read together, with the more specific protection often guiding the outcome.

Sources of international law compared

Movement doctrines compared