Acquisition and Loss of Territory

Acquisition and loss of territory concern the legal methods by which a State may acquire sovereignty over territory and the circumstances in which territorial sovereignty may cease or pass to another State. Territorial title is an important aspect of State sovereignty, and International Law regulates both the acquisition and loss of territory.

The traditional law recognised several modes of acquiring territory, but the development of modern International Law—particularly the prohibition on the use of force—has significantly changed the legal status of some traditional methods.

Meaning of Acquisition of Territory

Acquisition of territory means the establishment or transfer of lawful territorial sovereignty over a particular area in favour of a State.

A State may acquire territorial title through recognised legal means such as:

• occupation;
• prescription;
• cession;
• accession;
• decisions or settlements determining territorial title.

The traditional methods must be understood in light of modern International Law.

Meaning of Loss of Territory

Loss of territory occurs when a State ceases to possess sovereignty over a particular territory.

This may occur through:

• cession;
• lawful transfer;
• separation or secession;
• dissolution;
• merger or unification;
• abandonment in circumstances recognised by International Law;
• other legally recognised changes in territorial title.

Traditional Modes of Acquisition

The traditional modes of acquiring territory are commonly discussed as:

1. Occupation
2. Prescription
3. Cession
4. Accession
5. Conquest

However, conquest through unlawful force is no longer a lawful mode of acquiring territory under modern International Law.

Occupation

Occupation traditionally means the acquisition of territory that is terra nullius by taking possession of it with the intention of acquiring sovereignty.

Two elements are traditionally required:

Effective Possession

The State must exercise sufficient authority over the territory.

Intention to Acquire Sovereignty

The State must intend to act as sovereign over the territory.

Therefore:

Occupation = Effective possession + Intention to acquire sovereignty

Terra Nullius

Terra nullius refers to territory that is not subject to the sovereignty of any State.

Occupation as a mode of acquisition traditionally applies only where territory is genuinely terra nullius.

A State cannot invoke occupation to acquire territory already belonging to another State.

Effectivité in Occupation

The effectiveness of State authority may be relevant in determining whether occupation has taken place.

Relevant evidence may include:

• administration;
• legislation;
• law enforcement;
• public services;
• official acts;
• exercise of governmental authority.

However, the required degree of effective control depends upon the circumstances and nature of the territory.

Prescription

Prescription refers to the acquisition of territorial title through long, peaceful and continuous exercise of State authority over territory, particularly where another State with a competing claim has acquiesced or failed to effectively object.

Important elements traditionally considered include:

• peaceful possession;
• continuous exercise of authority;
• public exercise of sovereignty;
• passage of time;
• absence of effective objection by the competing State.

Acquiescence

Acquiescence means acceptance or tolerance inferred from the conduct or silence of a State in circumstances where an objection might reasonably have been expected.

It can be important in territorial disputes.

However:

Mere silence does not automatically establish acquiescence.

The circumstances must demonstrate that the conduct reasonably indicated acceptance.

Cession

Cession is the transfer of territory from one State to another by agreement.

It is normally achieved through:

• treaty;
• bilateral agreement;
• other valid international arrangement.

The essential feature is consent.

For example:

State A → Agreement → Territory → State B

Examples of Cession

Historical examples include:

• the transfer of Alaska from Russia to the United States;
• territorial transfers following peace treaties;
• other agreed transfers of sovereignty.

Cession differs from conquest because it is based upon the consent of the State transferring the territory.

Accession

Accession refers to the acquisition of additional territory through natural processes or, in some classifications, through the addition of territory to an existing State.

Natural accession may occur through:

• formation of islands;
• gradual deposition of soil;
• changes in river courses;
• other natural geographical processes.

The precise legal consequences depend upon the geographical circumstances.

Conquest

Conquest historically referred to the acquisition of territory through military victory.

Under the traditional law, military conquest could sometimes result in territorial title.

Modern International Law has fundamentally changed this position.

The prohibition on the threat or use of force means that a State cannot lawfully acquire another State’s territory through unlawful force.

Therefore:

Conquest through unlawful force is not a lawful mode of acquiring territorial sovereignty under modern International Law.

Prohibition on Acquisition of Territory by Force

Modern International Law protects territorial integrity and prohibits the use of force against the territorial integrity or political independence of States.

Consequently:

Military occupation + unlawful force ≠ Lawful territorial title

An occupying State does not automatically acquire sovereignty over the occupied territory.

Territorial Transfer

Territory may be transferred through a valid agreement between States.

This may result in:

• change of sovereignty;
• change in territorial boundaries;
• succession to certain rights and obligations.

The transfer must comply with applicable International Law.

Self-Determination and Acquisition of Territory

Modern International Law also recognises the importance of self-determination.

Where a people exercises a recognised right to self-determination, territorial changes may occur through:

• independence;
• decolonisation;
• other lawful processes.

Such situations cannot simply be analysed through the traditional methods of occupation or conquest.

Loss of Territory by Cession

Cession is both:

• a mode of acquisition for the receiving State; and
• a mode of loss for the transferring State.

Thus:

State A loses territory

↓

State B acquires territory

through:

Valid agreement

Loss of Territory Through Secession

Secession occurs when part of a State separates and establishes itself as a new State.

The original State loses sovereignty over the separated territory.

For example:

State A → Territory separates → State B

State A continues to exist but loses sovereignty over the separated territory.

Loss of Territory Through Dissolution

In dissolution, the predecessor State itself ceases to exist.

Its territory becomes divided among successor States.

For example:

State A → Dissolution → States B + C + D

The predecessor State therefore loses its entire territory because its international legal personality ceases to exist.

Loss Through Merger or Unification

When States unite, their separate territorial identities may be replaced by the territory of the unified State.

For example:

State A + State B → Unified State C

The predecessor States may cease to exist separately depending upon the legal structure of the unification.

Loss Through Natural Changes

Territorial changes may also result from natural geographical processes.

Examples include:

• erosion;
• accretion;
• changes in river courses;
• formation or disappearance of land.

The legal effect depends upon the specific circumstances and applicable rules concerning territorial boundaries.

Abandonment

Abandonment or dereliction has traditionally been discussed as a possible mode of loss of territory.

It involves:

1. withdrawal of State authority; and
2. intention to abandon sovereignty.

Mere absence or temporary lack of administration does not necessarily establish abandonment.

There must generally be evidence of an intention to relinquish territorial sovereignty.

Dereliction

Dereliction refers to the loss of territorial title through abandonment.

Two elements are generally considered:

Physical abandonment

Intention to abandon sovereignty

However, modern International Law treats territorial abandonment cautiously because sovereignty is not normally lost merely through temporary absence of governmental activity.

Loss of Territory Through Treaty

A State may voluntarily relinquish territory through an international agreement.

The treaty may:

• transfer sovereignty;
• establish a new boundary;
• recognise another State’s title.

This is essentially a form of cession.

Loss Through State Succession

State succession can result in the loss or transfer of territorial sovereignty.

This may occur through:

• secession;
• dissolution;
• unification;
• territorial transfer;
• decolonisation.

The legal consequences depend upon the particular form of succession.

Acquisition vs Recognition

Acquisition of territory and recognition are separate concepts.

Acquisition of Territory

Concerns the legal basis for obtaining territorial sovereignty.

Recognition

Concerns acceptance by another State of a particular legal or political status.

Recognition may provide evidence concerning territorial title but does not automatically create title.

Territorial Title and Effective Control

Effective control may be relevant to territorial title but is not necessarily decisive.

A State may exercise de facto control without possessing lawful territorial title.

Therefore:

Effective control does not automatically equal lawful sovereignty.

This distinction is particularly important in situations involving military occupation.

Important Cases

Island of Palmas Arbitration, 1928

The Island of Palmas case is a leading authority concerning territorial title.

The tribunal emphasised the importance of the continuous and peaceful display of State authority over territory.

It is particularly important for understanding:

• effective control;
• territorial title;
• discovery;
• sovereignty.

Eastern Greenland Case, 1933

The case concerned competing claims to sovereignty over Eastern Greenland.

It examined:

• State intention;
• governmental acts;
• exercise of authority;
• territorial sovereignty.

Legal Status of Eastern Greenland

The case demonstrates that territorial sovereignty can be established through relevant State conduct and the legal circumstances surrounding territorial claims.

Temple of Preah Vihear, 1962

The case concerned sovereignty over the Temple of Preah Vihear.

The Court considered:

• maps;
• conduct of the parties;
• acceptance;
• acquiescence;
• territorial title.

Western Sahara, 1975

The Western Sahara Advisory Opinion is important for understanding territorial status, historical claims and self-determination.

It demonstrates that historical connections do not automatically override the right of peoples to self-determination.

Nicaragua v. United States, 1986

The case reinforced the principles of:

• territorial sovereignty;
• non-intervention;
• prohibition on the use of force.

It is important for understanding why unlawful military intervention cannot establish lawful territorial rights.

Acquisition and Loss of Territory

Acquisition	Loss
Occupation	Cession
Prescription	Secession
Cession	Dissolution
Accession	Unification
Lawful territorial settlement	Transfer of territory
Self-determination in appropriate circumstances	Self-determination in appropriate circumstances

Traditional vs Modern Law

Traditional Approach	Modern International Law
Conquest sometimes treated as a mode of acquisition	Unlawful conquest is not recognised
Military victory could produce title	Force cannot lawfully create territorial title
Occupation had broader historical application	Occupation cannot justify acquisition of another State’s territory
Territorial acquisition focused heavily on State practice	Territorial integrity and self-determination are central
Consent and effective control were major considerations	They remain relevant subject to modern legal limitations

Common Confusions

Is conquest still a lawful method of acquiring territory?

No. Unlawful use of force cannot create lawful territorial title.

Does occupation transfer sovereignty?

No. Occupation does not automatically transfer sovereignty.

Is occupation the same as conquest?

No. Occupation concerns effective control of territory; conquest historically concerned acquisition through military victory. Modern International Law does not recognise unlawful conquest as a lawful mode of acquisition.

Is cession based on force?

No. Cession is based upon the consent of the State transferring the territory.

Can a State lose territory through secession?

Yes. The separating territory may become a new State while the original State continues.

Does dissolution involve loss of only part of the territory?

No. In dissolution, the predecessor State ceases to exist and its territory is divided among successor States.

Does effective control automatically establish sovereignty?

No. Effective control is evidence relevant to territorial title but does not necessarily establish lawful sovereignty.

Can natural geographical changes affect territory?

Yes. Accretion, erosion and changes in rivers can have territorial consequences depending upon the circumstances.

Is abandonment automatic if a State stops administering territory?

No. Abandonment traditionally requires both withdrawal of authority and intention to relinquish sovereignty.

Topic at a Glance

Mode	Nature	Effect
Occupation	Acquisition	Territory not under another State’s sovereignty may be acquired through effective possession
Prescription	Acquisition	Title may arise from prolonged peaceful exercise of sovereignty under appropriate circumstances
Cession	Acquisition/Loss	Territory transferred by agreement
Accession	Acquisition	Territory added through natural processes
Conquest	Historical mode	Unlawful conquest no longer creates lawful title
Secession	Loss/Acquisition	Part separates and forms a new State
Dissolution	Loss	Predecessor State ceases to exist
Unification	Loss/Combination	States combine into a unified State
Dereliction	Loss	Abandonment of sovereignty with intention to relinquish

Quick Revision

• Acquisition of territory means obtaining lawful territorial sovereignty.
• Loss of territory means cessation or transfer of sovereignty over territory.
• Traditional modes of acquisition include:
  • occupation;
  • prescription;
  • cession;
  • accession;
  • conquest.
• Occupation traditionally requires effective possession and intention to acquire sovereignty over territory that is terra nullius.
• Prescription involves prolonged and peaceful exercise of sovereignty under appropriate circumstances.
• Cession is transfer of territory by agreement.
• Accession involves natural addition of territory.
• Conquest is no longer a lawful method where territory is acquired through unlawful force.
• Territory may be lost through:
  • cession;
  • secession;
  • dissolution;
  • unification;
  • lawful territorial transfer;
  • dereliction in appropriate circumstances.
• Effective control does not automatically establish lawful territorial title.
• Occupation does not automatically transfer sovereignty.
• Territorial integrity and self-determination are central principles of modern International Law.
• Island of Palmas is a leading authority on territorial title and effective exercise of sovereignty.
• Eastern Greenland, Temple of Preah Vihear, Western Sahara and Nicaragua v. United States are important authorities.
• The essential principle is:

Territorial sovereignty can be acquired or lost only through legally recognised processes; unlawful force cannot create lawful territorial title.

Conclusion

The acquisition and loss of territory are governed by principles that have developed significantly from traditional International Law to the modern international legal order. Traditional methods of acquisition included occupation, prescription, cession, accession and conquest. While occupation, prescription, cession and accession remain relevant in appropriate circumstances, conquest through unlawful force is no longer recognised as a lawful means of acquiring territory. Territory may be lost through cession, secession, dissolution, unification, lawful territorial transfer or, in appropriate circumstances, abandonment. The legal assessment of territorial title requires consideration of treaties, State conduct, effective exercise of authority, acquiescence, territorial integrity and self-determination. Cases such as Island of Palmas, Eastern Greenland, Temple of Preah Vihear and Western Sahara demonstrate the importance of legal title and State conduct, while Nicaragua reinforces the prohibition on using force to interfere with another State’s territorial sovereignty.