Succession to Treaties

Succession to treaties concerns the effect of a change of State responsibility for a territory on the treaty rights and obligations applicable to that territory. It is one of the most important aspects of State succession because a change in sovereignty does not necessarily produce the same result for every treaty.

The answer depends upon the type of State succession, the nature of the treaty, and the applicable rules of International Law. The principal framework is provided by the Vienna Convention on Succession of States in Respect of Treaties, 1978.

Meaning of Succession to Treaties

Succession to treaties refers to the question of whether treaties of the predecessor State continue to apply to the territory after a successor State replaces it.

The basic question is:

Does the successor State inherit the treaty rights and obligations of the predecessor State?

There is no single rule applicable to every treaty or every form of succession.

Predecessor and Successor State

Predecessor State

The State that was previously responsible for the international relations of the territory.

Successor State

The State that replaces the predecessor State in responsibility for the territory.

For example:

State A → Treaty applies → State B replaces State A → Does the treaty continue?

The answer depends upon the particular circumstances.

Vienna Convention on Succession of States in Respect of Treaties, 1978

The Vienna Convention on Succession of States in Respect of Treaties, 1978 is the principal treaty dealing specifically with succession to treaties.

It addresses different forms of succession, including:

• transfer of territory;
• newly independent States;
• unification;
• separation;
• dissolution.

The Convention distinguishes between different categories of treaties and different forms of succession.

General Principle

The general position cannot be reduced to either:

All treaties continue

or

All treaties terminate.

Instead:

Type of succession + Nature of treaty + Applicable rule → Treaty consequence

This is essential when answering examination questions.

Succession in Respect of Part of Territory

Where part of the territory of a State is transferred to another State, the treaty position may change for that territory.

A treaty applicable to the territory may cease to apply there if the successor State’s treaty regime becomes applicable.

This is sometimes described through the principle of moving treaty frontiers.

Moving Treaty Frontiers Principle

Under the moving treaty frontiers principle, when territory becomes part of another State, the treaties of the predecessor State do not automatically continue to apply to that territory simply because they previously applied there.

Instead, the treaty regime of the successor State generally becomes applicable, subject to the relevant rules and exceptions.

Thus:

Territory moves from State A → State B’s treaty regime may become applicable

This principle is particularly relevant to territorial transfers.

Newly Independent States

A newly independent State is a State that has emerged from a territory that was previously dependent upon another State and has become independent.

The rules concerning newly independent States are particularly influenced by the clean slate principle.

Clean Slate Principle

The clean slate principle means that a newly independent State is generally not automatically bound by all treaties that previously applied to the territory under the predecessor State.

The principle was particularly important during the process of decolonisation.

The underlying idea is:

A newly independent State should not automatically inherit the entire treaty system of the colonial predecessor merely because those treaties previously applied to the territory.

However, the clean slate principle is subject to important qualifications.

Treaty Continuity for Newly Independent States

Although the clean slate principle is important, it does not mean that every treaty simply disappears.

Certain treaties may continue or be subject to special rules, particularly where they concern:

• boundaries;
• territorial arrangements;
• rights connected with territory.

The nature of the treaty must therefore always be considered.

Boundary Treaties

Boundary treaties are treated differently from ordinary political treaties.

A change in sovereignty does not normally invalidate an existing international boundary.

This reflects the importance of:

• territorial stability;
• certainty of borders;
• peaceful international relations.

Therefore:

State succession ≠ Automatic Redrawing of Boundaries

Territorial Regimes

Treaties establishing territorial regimes may also continue despite State succession.

These may concern:

• boundaries;
• territorial status;
• rights over particular territories;
• permanent territorial arrangements.

The reason is that such obligations are closely connected with the territory itself rather than merely with the political identity of the predecessor Government.

Treaties of a Political or Personal Character

Treaties that are closely connected with the political or personal relationship of the predecessor State may not automatically continue.

Examples may include certain:

• political alliances;
• defence arrangements;
• personal arrangements between Governments.

Their continuation depends upon the nature of the succession and the applicable legal rules.

Bilateral Treaties

Bilateral treaties involve two parties.

After State succession, the continuation of a bilateral treaty may depend upon:

• agreement between the successor State and the other party;
• conduct indicating acceptance;
• the nature of the treaty;
• the applicable succession rules.

The other party to the treaty therefore has an important role in determining whether the treaty relationship continues.

Multilateral Treaties

Multilateral treaties involve several States.

The position of a successor State may depend upon:

• the nature of the treaty;
• the rules of the treaty itself;
• the type of succession;
• notification or participation by the successor State;
• the practice of the parties.

A successor State does not automatically acquire every right or obligation under every multilateral treaty.

Treaties Establishing International Organisations

Special considerations may arise where a treaty is the constituent instrument of an international organisation.

Membership in an international organisation is generally governed by the organisation’s own constitutional rules.

Therefore:

State succession does not automatically guarantee succession to membership in every international organisation.

Succession and Treaty Rights

Succession may concern both:

• treaty obligations; and
• treaty rights.

A successor State may need to determine whether it can exercise rights previously belonging to the predecessor State.

The answer depends upon the nature of the treaty and the applicable succession rules.

Succession and Treaty Obligations

Similarly, the successor State may or may not inherit treaty obligations.

Factors may include:

• type of succession;
• nature of the treaty;
• territorial connection;
• agreement between the States;
• applicable customary rules.

Succession and Bilateral Treaties

A bilateral treaty generally requires particular attention because it creates a legal relationship between two States.

For a successor State, the continuation of such a relationship may depend upon acceptance by the other treaty party.

Thus:

Successor State + Other Treaty Party → Agreement/acceptance may be relevant

Succession and Multilateral Treaties

For multilateral treaties, the situation can be more complex.

A successor State may:

• continue participation;
• accede to the treaty;
• establish its status through notification;
• remain outside the treaty.

The applicable result depends upon the treaty and the type of succession.

Unification of States

Where two or more States unite and form a single State, the treaty position is generally considered in light of the continuing legal relationships of the predecessor States.

The successor State may continue certain treaty obligations, subject to the applicable rules.

The specific consequences may differ according to the nature of the unification.

Separation or Secession

Where part of a State separates and becomes a new State, treaty succession questions arise for both:

• the continuing State; and
• the newly emerging State.

The 1978 Vienna Convention contains rules specifically addressing situations of separation of parts of a State.

Dissolution of States

In dissolution, the predecessor State ceases to exist and several successor States emerge.

This creates complex questions concerning:

• bilateral treaties;
• multilateral treaties;
• territorial arrangements;
• international organisations;
• treaty rights and obligations.

The treaty position may need to be determined separately for each successor State.

State Succession and Treaty Registration

A successor State may need to undertake appropriate formal steps to establish its participation in particular treaties.

This may involve:

• notification;
• declaration;
• succession procedures;
• depositary communications.

The exact procedure depends upon the treaty and applicable rules.

State Succession and Treaty Reservations

Questions may also arise concerning reservations made by the predecessor State.

A successor State’s position regarding those reservations depends upon the relevant treaty and succession rules.

The successor State may not necessarily be bound by every reservation simply because the predecessor State had made it.

State Succession and Treaty Termination

State succession does not automatically mean that every treaty is terminated.

Likewise, succession does not automatically mean that every treaty continues.

The correct approach is to determine:

1. the type of succession;
2. the nature of the treaty;
3. the territorial connection;
4. the applicable rule.

Important Distinction: State Succession vs Government Change

A change of Government is not normally State succession.

If:

Government A → Government B

while:

State A continues

then the treaties of State A generally continue because the international legal personality of the State has not changed.

This is fundamentally different from:

State A → State B

where State succession questions arise.

State Succession and International Boundaries

Boundary treaties are especially important because international law strongly favours stability of boundaries.

A successor State generally cannot simply argue:

“A new State has emerged, therefore all previous boundaries have disappeared.”

Existing international boundaries are generally preserved unless changed in accordance with applicable international law.

State Succession and Self-Determination

Newly independent States often emerge through the exercise of self-determination.

The treaty consequences of decolonisation must therefore be considered alongside:

• independence;
• territorial integrity;
• self-determination;
• continuity of territorial arrangements.

Important Examples

Decolonisation

The emergence of numerous Asian and African States after decolonisation raised major questions concerning whether newly independent States would inherit the treaties concluded by colonial powers.

The clean slate approach became particularly important in this context.

Dissolution of Yugoslavia

The dissolution of Yugoslavia raised complex questions concerning treaty continuity and the status of the successor States.

Dissolution of the Soviet Union

The dissolution of the Soviet Union raised questions concerning:

• treaty obligations;
• multilateral treaties;
• international organisation membership;
• State continuity.

Important International Instrument

Vienna Convention on Succession of States in Respect of Treaties, 1978

The Convention is the principal international instrument dealing with succession to treaties.

Its major areas include:

• newly independent States;
• transfer of territory;
• unification;
• separation;
• dissolution.

It provides a structured framework for determining the treaty consequences of State succession.

Common Confusions

Does a successor State automatically inherit all treaties?

No. The answer depends upon the type of succession and the nature of the treaty.

Does the clean slate principle apply to every successor State?

No. It is particularly associated with newly independent States.

Do boundary treaties disappear after State succession?

Generally, no. Boundary arrangements receive special protection.

Does State succession terminate every bilateral treaty?

No. The continuation of bilateral treaties depends upon the circumstances and applicable rules.

Does a new Government create treaty succession?

No. A change of Government normally does not constitute State succession.

Does State succession automatically transfer UN membership?

No. Membership in an international organisation is governed by its own rules and practice.

Are territorial treaties treated like ordinary political treaties?

No. Territorial and boundary arrangements may receive special treatment because of their connection with the territory.

Topic at a Glance

Point	Position
Subject	Succession to Treaties
Main question	Whether predecessor’s treaty rights and obligations continue
Principal instrument	Vienna Convention, 1978
Newly independent States	Clean slate principle generally relevant
Territorial transfer	Moving treaty frontiers principle relevant
Boundary treaties	Generally preserved
Bilateral treaties	May depend upon agreement/acceptance
Multilateral treaties	Depends on treaty and succession rules
Political treaties	May not automatically continue
International organisations	Governed by their own rules
Government change	Normally not State succession

Quick Revision

• Succession to treaties concerns the effect of State succession on treaty rights and obligations.
• The principal international instrument is the Vienna Convention on Succession of States in Respect of Treaties, 1978.
• There is no universal rule that all treaties either continue or terminate.
• The result depends upon:
  • type of succession;
  • nature of treaty;
  • territorial connection;
  • applicable legal rules.
• The clean slate principle is particularly associated with newly independent States.
• Under the clean slate approach, a newly independent State is not automatically bound by all predecessor treaties.
• Boundary treaties generally continue despite State succession.
• Territorial arrangements receive special treatment.
• In territorial transfer, the treaty regime of the successor State may replace that of the predecessor.
• Bilateral treaties may require agreement or acceptance by the other treaty party.
• Multilateral treaty succession depends upon the treaty, succession circumstances and applicable procedures.
• Unification, separation and dissolution raise distinct treaty succession questions.
• Membership of international organisations is generally governed by the constitutional rules of the organisation.
• A change of Government is not normally State succession.
• State succession does not automatically terminate every treaty.
• State succession does not automatically continue every treaty.
• The essential principle is:

The effect of State succession on treaties depends upon the type of succession and the nature of the treaty; there is no single rule applicable to every treaty.

Conclusion

Succession to treaties concerns the continuation, modification or termination of treaty rights and obligations following a change in the State responsible for the international relations of a territory. The Vienna Convention on Succession of States in Respect of Treaties, 1978 provides the principal framework for analysing these questions. Newly independent States are particularly associated with the clean slate principle, while territorial and boundary treaties receive special treatment because of their close connection with territory. Bilateral and multilateral treaties may produce different consequences, and the treaty’s own provisions may also be relevant. In cases of unification, separation and dissolution, the treaty position must be determined according to the particular form of succession. Above all, State succession must be distinguished from a change of Government, because a change in Government normally leaves the State’s existing treaty relationships intact.