Codification and progressive development are important processes through which Public International Law is clarified, organised and developed. International law is not contained in a single comprehensive legal code. Its rules arise from treaties, customary international law, general principles and other recognised legal materials. Codification brings existing rules into a more precise and systematic written form, while progressive development seeks to formulate new rules or extend existing rules to address areas where international law is insufficient or developing.
- Meaning of Codification
- Meaning of Progressive Development
- Codification vs Progressive Development
- Legal Basis
- Role of the United Nations
- International Law Commission
- Functions of the International Law Commission
- Codification Through Treaties
- Vienna Convention on Diplomatic Relations, 1961
- Vienna Convention on the Law of Treaties, 1969
- United Nations Convention on the Law of the Sea
- Progressive Development Through the ILC
- Draft Articles on State Responsibility
- Draft Articles on Diplomatic Protection
- Codification and Customary International Law
- Codification Does Not Automatically Bind All States
- Progressive Development and State Consent
- Role of State Practice
- Role of Juristic Writings
- Role of Judicial Decisions
- Importance of Codification
- Importance of Progressive Development
- Challenges
- Important Cases
- Codification vs Consolidation
- Codification vs Unification
- Common Confusions
- Topic at a Glance
- Quick Revision
- Conclusion
The two concepts are closely connected but are not identical. Codification primarily concerns the systematic formulation of existing law, whereas progressive development involves the creation or development of rules in areas where sufficient existing law may not yet exist.
Meaning of Codification
Codification means the systematic collection, clarification and formulation of existing rules of international law into written instruments.
The purpose is to make international law:
- clearer;
- more precise;
- systematic;
- accessible;
- predictable;
- easier to apply.
Codification may concern rules that already exist in customary international law and may eventually result in their incorporation into a multilateral treaty.
Meaning of Progressive Development
Progressive development refers to the formulation of new rules of international law or the development of existing rules in areas where the law is insufficiently developed.
It becomes particularly important when:
- State practice is developing;
- existing rules are unclear;
- new international problems arise;
- technological developments create new legal questions;
- existing law does not adequately regulate a particular issue.
Progressive development therefore has a more creative element than codification.
Codification vs Progressive Development
| Point | Codification | Progressive Development |
|---|---|---|
| Main purpose | Formulate and systematise existing law | Develop new or emerging rules |
| Existing legal basis | Generally established rules already exist | Existing law may be incomplete or insufficient |
| Nature | Clarificatory and systematic | Developmental and sometimes innovative |
| Main source | Existing State practice and customary rules | Emerging practice, policy considerations and legal development |
| Result | Written formulation of existing rules | New or further-developed legal rules |
Legal Basis
Article 13(1)(a) of the UN Charter
Article 13(1)(a) provides that the General Assembly shall initiate studies and make recommendations for the purpose of:
βencouraging the progressive development of international law and its codification.β
This provision gives the United Nations an important institutional role in the development and codification of international law.
Role of the United Nations
The United Nations has played a central role in both codification and progressive development.
The UN provides a framework through which States can:
- examine existing international law;
- identify areas requiring development;
- negotiate international conventions;
- formulate draft rules;
- establish specialised legal institutions;
- promote uniformity in international legal standards.
The International Law Commission (ILC) is the principal UN body responsible for the systematic development and codification of international law.
International Law Commission
The International Law Commission was established by the UN General Assembly in 1947.
Its principal function is to assist in:
- codification of international law;
- progressive development of international law.
The Commission consists of independent legal experts elected by the General Assembly.
Members serve in their personal capacity rather than as representatives of their governments.
Functions of the International Law Commission
The ILC performs several important functions.
1. Selection of Topics
The Commission identifies areas of international law suitable for study and development.
2. Study of Existing Law
It examines:
- State practice;
- treaties;
- judicial decisions;
- national legislation;
- scholarly writings;
- previous international instruments.
3. Preparation of Draft Articles
The Commission may prepare draft articles dealing with particular areas of international law.
4. Consultation with States
States are given opportunities to submit observations and comments on draft texts.
5. Final Draft
After extensive consideration, the Commission may adopt a final set of draft articles or other conclusions.
6. Submission to the General Assembly
The final work may be submitted to the UN General Assembly for consideration.
The General Assembly may then:
- take note of the work;
- recommend it to States;
- convene a diplomatic conference;
- incorporate it into a treaty;
- otherwise encourage its development.
Codification Through Treaties
One of the most important methods of codification is the adoption of multilateral treaties.
A treaty can transform a body of customary rules into a clearly written legal instrument.
Examples include conventions dealing with:
- diplomatic relations;
- consular relations;
- law of treaties;
- law of the sea;
- international humanitarian law.
However, codification does not necessarily mean that the resulting treaty is binding upon every State.
A State generally becomes bound by a treaty according to the applicable rules concerning consent to be bound.
Vienna Convention on Diplomatic Relations, 1961
The Vienna Convention on Diplomatic Relations, 1961 provides a major example of codification.
Many rules concerning diplomatic relations had developed through State practice and customary international law.
The Convention systematised these rules in a comprehensive written instrument.
It also established detailed provisions concerning:
- diplomatic agents;
- diplomatic missions;
- privileges and immunities;
- functions of diplomatic missions;
- termination of diplomatic functions.
Vienna Convention on the Law of Treaties, 1969
The Vienna Convention on the Law of Treaties, 1969 is another major example.
It codified and developed rules concerning:
- conclusion of treaties;
- consent to be bound;
- reservations;
- interpretation;
- amendment;
- termination;
- suspension;
- invalidity.
The Convention is often regarded as a major codification of the law of treaties.
United Nations Convention on the Law of the Sea
The United Nations Convention on the Law of the Sea, 1982 provides another important example.
It brought together extensive rules concerning:
- territorial seas;
- contiguous zones;
- exclusive economic zones;
- continental shelves;
- high seas;
- marine scientific research;
- protection of the marine environment;
- dispute settlement.
The Convention also developed legal rules beyond merely reproducing previously established customary law.
Progressive Development Through the ILC
The ILC does not merely reproduce existing law.
Its work can involve two distinct activities:
Codification
Formulating rules where sufficient State practice and legal materials already exist.
Progressive Development
Preparing proposals concerning subjects where international law has not yet been sufficiently developed.
The two activities may occur within the same project.
Draft Articles on State Responsibility
The ILCβs work on the Articles on Responsibility of States for Internationally Wrongful Acts, 2001 is a major example.
The Articles contain rules concerning:
- internationally wrongful acts;
- attribution;
- breach of international obligations;
- circumstances precluding wrongfulness;
- consequences of responsibility;
- reparation;
- countermeasures.
The Articles combine elements of codification and progressive development.
They are not themselves a treaty, but many of their provisions are regarded as reflecting customary international law, while the precise status of individual provisions must be assessed separately.
Draft Articles on Diplomatic Protection
The ILC also developed the Draft Articles on Diplomatic Protection, 2006.
The work addressed questions concerning:
- diplomatic protection;
- nationality of claims;
- exhaustion of local remedies;
- legal consequences of diplomatic protection.
The project demonstrates how the ILC can systematise existing international law while also addressing areas requiring further development.
Codification and Customary International Law
Codification has a close relationship with customary international law.
A treaty resulting from codification may:
1. Record Existing Custom
A treaty provision may simply express an already existing customary rule.
2. Crystallise Emerging Custom
A treaty may help establish a customary rule that was still developing.
3. Contribute to New Custom
A treaty provision may influence subsequent State practice and opinio juris and contribute to the emergence of a customary rule.
4. Create Treaty Rules
A treaty may also create obligations binding specifically upon its parties without the rule necessarily becoming customary international law.
Codification Does Not Automatically Bind All States
An important distinction must be made between codification and universal binding force.
The adoption of a codifying treaty does not automatically make every State a party to the treaty.
A State that has not accepted the treaty is generally not bound by the treaty merely because it exists.
However, a provision may independently bind a non-party State if it reflects customary international law or another applicable legal rule.
Progressive Development and State Consent
Progressive development must operate within the structure of international law.
International organisations and expert bodies cannot simply legislate universally for States without an appropriate legal basis.
Progressive development often involves:
- negotiation;
- State participation;
- diplomatic conferences;
- adoption of treaties;
- subsequent State practice.
State consent remains important in transforming proposed rules into binding treaty obligations.
Role of State Practice
State practice is important in both codification and progressive development.
For codification, practice helps identify the rules that already exist.
For progressive development, emerging practice may indicate the direction in which international law is developing.
States may express their legal positions through:
- legislation;
- diplomatic correspondence;
- international negotiations;
- official statements;
- judicial decisions;
- treaty practice;
- votes and explanations of votes.
Role of Juristic Writings
Scholarly writings can assist the codification process by:
- identifying existing customary rules;
- analysing State practice;
- comparing legal systems;
- identifying areas of uncertainty;
- proposing possible legal developments.
However, scholarly proposals do not themselves become binding international law.
Role of Judicial Decisions
Judicial decisions assist codification and progressive development by:
- clarifying existing rules;
- identifying customary international law;
- interpreting treaties;
- developing legal concepts;
- resolving disputes concerning emerging areas of law.
Judicial decisions remain a subsidiary means under Article 38(1)(d) of the ICJ Statute.
Importance of Codification
Codification provides several benefits.
Clarity
Written rules are generally easier to identify and interpret.
Certainty
Codification reduces uncertainty concerning the content of international law.
Uniformity
Common written rules can promote consistency among States.
Accessibility
Codified rules are easier for governments, courts, organisations and practitioners to locate.
Development of International Cooperation
Codification can create common legal frameworks for international cooperation.
Importance of Progressive Development
Progressive development allows international law to respond to changing circumstances.
It is particularly important in areas affected by:
- technological development;
- environmental challenges;
- international economic relations;
- new forms of armed conflict;
- human rights developments;
- emerging international institutions.
It prevents international law from remaining permanently limited to rules developed in earlier historical periods.
Challenges
Different State Interests
States may have different political, economic and security interests.
Reaching agreement on new rules can therefore be difficult.
Lack of Uniform Practice
Progressive development may occur before sufficient State practice has emerged.
State Sovereignty
States may resist rules that they believe restrict their sovereignty or national interests.
Political Compromise
International negotiations often require compromises that may produce broadly worded legal provisions.
Binding Force
A draft text prepared by an international body does not automatically have the same legal force as a treaty or customary rule.
Important Cases
North Sea Continental Shelf Cases, 1969
The ICJ examined the relationship between treaty provisions and customary international law.
The case is important for understanding how treaty rules may influence the development or recognition of customary international law.
Nicaragua v. United States, 1986
The ICJ considered customary international law alongside treaty obligations.
The case demonstrates that treaty law and customary law may operate simultaneously and that customary rules may have an independent legal existence.
GabΔΓkovo-Nagymaros Project, 1997
The ICJ considered treaty obligations, environmental concerns and the development of international environmental law.
The case demonstrates how international law can respond to changing environmental considerations while applying existing legal obligations.
Legality of the Threat or Use of Nuclear Weapons, 1996
The ICJ examined treaty and customary rules concerning the use of nuclear weapons.
The advisory opinion demonstrates the interaction between existing international law and developing areas of legal regulation.
Codification vs Consolidation
These concepts should not be confused.
Codification
Systematic formulation of rules of international law into a clearer and more organised form.
Consolidation
Broader process of bringing together existing legal rules or instruments.
Codification generally has a more specific legal meaning concerning the formulation of international law.
Codification vs Unification
Codification
Organises and formulates existing international legal rules.
Unification
Seeks to establish uniform rules across different legal systems or jurisdictions.
The two processes can overlap, but they are not identical.
Common Confusions
Does codification create new international law?
Not necessarily.
Codification primarily formulates and systematises existing law, although codification projects may also contribute to progressive development.
Does a codifying treaty bind every State?
No.
Treaty obligations generally bind States according to their consent and the applicable rules of treaty law.
Is every ILC draft article legally binding?
No.
Draft articles are not automatically treaties or binding law merely because the ILC has adopted them.
Is progressive development the same as codification?
No.
Codification focuses mainly on existing law, while progressive development concerns the formulation or further development of rules where the law is incomplete or emerging.
Can progressive development ignore State practice?
No.
Although progressive development may involve developing new rules, State practice, legal considerations and participation of States remain important.
Is the ILC a world legislature?
No.
The ILC is an expert body that assists the UN in the progressive development and codification of international law. It does not possess unlimited legislative power over States.
Topic at a Glance
| Point | Position |
|---|---|
| Subject | Codification and Progressive Development |
| Main legal basis | Article 13(1)(a), UN Charter |
| Principal body | International Law Commission |
| ILC established | 1947 |
| Codification | Systematic formulation of existing law |
| Progressive development | Development of new or emerging rules |
| Major method | Drafting and adoption of international conventions |
| Custom | Important basis for codification |
| State practice | Important in identifying and developing rules |
| Key examples | Vienna Convention on Diplomatic Relations, Vienna Convention on Law of Treaties, UNCLOS |
| Important ILC work | State Responsibility Articles, 2001 |
| Main limitation | Draft texts do not automatically become binding law |
Quick Revision
- Codification means systematically formulating and organising existing rules of international law.
- Progressive development involves developing new rules or further developing areas where international law is insufficient.
- Article 13(1)(a) of the UN Charter refers to the progressive development and codification of international law.
- The International Law Commission (ILC) was established in 1947.
- The ILC is the principal UN body dealing with codification and progressive development.
- Codification is primarily concerned with existing law.
- Progressive development has a more creative and developmental character.
- Both processes may occur within the same international law project.
- Codification frequently results in multilateral treaties.
- The Vienna Convention on Diplomatic Relations, 1961 is an important example.
- The Vienna Convention on the Law of Treaties, 1969 is another major example.
- UNCLOS 1982 contains both codified and progressively developed rules.
- The 2001 Articles on State Responsibility combine codification and progressive development.
- ILC draft articles are not automatically binding merely because the ILC adopts them.
- Codifying treaties do not automatically bind non-party States.
- Treaty provisions may codify existing custom, crystallise emerging custom or contribute to new customary rules.
- State practice and opinio juris remain important in identifying customary international law.
- Judicial decisions and juristic writings assist the codification process but do not themselves automatically create binding rules.
- The North Sea Continental Shelf Cases are important for the relationship between treaties and customary law.
- Nicaragua v. United States demonstrates the parallel operation of treaty and customary rules.
- The GabΔΓkovo-Nagymaros Project illustrates the development of international environmental law.
- Progressive development allows international law to respond to emerging international problems.
- Neither the ILC nor the UN functions as a universal legislature with unlimited authority over sovereign States.
Conclusion
Codification and progressive development are essential mechanisms through which Public International Law becomes clearer, more systematic and responsive to changing international conditions. Codification primarily seeks to formulate and organise existing rules, while progressive development addresses areas where international law is incomplete or evolving. The United Nations, particularly through the International Law Commission, plays a central role in both processes. The resulting work may take the form of draft articles, declarations or international conventions. Codification can clarify customary law, while progressive development can contribute to the emergence of new legal rules. However, draft texts and resolutions do not automatically possess binding force. Their legal status depends upon the applicable treaty rules, customary international law and the acceptance and practice of States.
