State Territorial Sovereignty — Acquisition and Loss of Territory — Public International Law Notes

State Territorial Sovereignty — Acquisition and Loss of Territory

In 1928, an arbitrator had to decide whether the Island of Palmas (near the Philippines) belonged to the United States (which claimed through Spain’s discovery) or the Netherlands (which had quietly administered it for two centuries). Max Huber ruled for the Netherlands and gave international law its most-quoted line: a mere claim by discovery is an inchoate title that yields to the “continuous and peaceful display of the functions of a State”. Nearly every island problem you will ever be set is decided by that sentence.

How a State gains and loses territory

Territory is the physical basis of statehood, and territorial sovereignty is a State’s exclusive right to exercise the functions of a State over it. International law recognises a closed list of ways to acquire territory — and a matching list of ways to lose it. Learn the five modes of acquisition, each with its matching mode of loss.

A. Occupation

Acquiring terra nullius [land belonging to no one] by taking possession of it. It requires two things: animus occupandi (the intention to acquire sovereignty) and effective, continuous and peaceful display of State authority (corpus) — actual administration, not a flag planted and forgotten. Mere discovery gives only an inchoate (incomplete) title that must be perfected by effective occupation within a reasonable time. Contiguity (mere nearness to one’s coast) is not a mode of acquisition (Island of Palmas, 1928; Clipperton Island, 1931). Loss counterpart: dereliction/abandonment (leaving with intent to give up).

B. Prescription

Acquiring territory that did belong to another State by long, continuous, peaceful and undisturbed possession (adverse possession between States), with the acquiescence of the former sovereign. The difference from occupation: occupation is of terra nullius, prescription is of territory that had an owner who lost it by inaction. Loss counterpart: the former sovereign loses by its own acquiescence.

C. Cession

Transfer of territory by agreement (treaty) from one State to another — by sale (Alaska, USA from Russia, 1867), gift, or exchange. The transferee gets exactly the title the transferor had (nemo dat quod non habet — no one can give what he does not have). Loss counterpart: the ceding State loses by the same treaty.

D. Annexation / Conquest (subjugation)

Historically, acquiring territory by conquest followed by annexation (formal declaration of taking) after defeating and subjugating the enemy. Note the modern limit: since the UN Charter (Art. 2(4), 1945) prohibits the threat or use of force, title acquired by conquest is no longer valid — the Stimson Doctrine of non-recognition of forcible acquisition is now general law. Loss counterpart: the defeated State loses (historically).

E. Accretion

Natural additions to territory — new land formed by the slow deposit of soil (alluvion), a river shifting course, or a new island rising in territorial waters. No formal act is needed; the new land follows the sovereignty of the land it attaches to. Loss counterpart: erosion.

Island of Palmas Case (Netherlands v. USA, 1928): “the continuous and peaceful display of territorial sovereignty (peaceful in relation to other States) is as good as a title… Discovery alone, without any subsequent act, cannot suffice to prove sovereignty.”

In Simple Terms: Owning land as a State is not about who saw it first or whose coast it is near — it is about who actually ran it, openly and peacefully, over time. A paper claim (discovery, contiguity) loses to real, continuous administration. And since 1945, you cannot get valid title by conquering it.

🧩 WORKED EXAMPLE — discovery vs effective control (the island problem)

Facts. State A claims a small island because its explorers discovered it centuries ago but never governed it. State B has openly administered it — patrols, licences, a post — for about 300 years.

Rule. Occupation requires effective, continuous, peaceful display of State authority; discovery gives only an inchoate title (Island of Palmas, 1928).

Apply. The decoy is that “discovery sounds like a complete root of title”. It is not — A’s discovery, never perfected by administration, is inchoate. B’s long, peaceful, effective control is the stronger title.

Conclusion. The island belongs to B. (Variant: if A had contiguity only, same result — nearness is not a mode of acquisition; Clipperton Island, 1931.)

flowchart TD
    A["Acquisition of territory"]
    A --> B["Occupation<br/>terra nullius + effective control"]
    A --> C["Prescription<br/>long possession of another's land"]
    A --> D["Cession<br/>transfer by treaty"]
    A --> E["Annexation/conquest<br/>now invalid: Art. 2(4) UN Charter"]
    A --> F["Accretion<br/>natural additions"]
    classDef box fill:#e8f0fe,stroke:#333,color:#111;
    class A,B,C,D,E,F box;

Case Laws

• Island of Palmas Case (Netherlands v. USA, 1928) — continuous, peaceful display of State authority beats a bare discovery title; discovery is only inchoate.
• Clipperton Island Arbitration (France v. Mexico, 1931) — for a remote, uninhabited island a minimal but real assertion of authority perfects occupation; contiguity is not enough.
• Legal Status of Eastern Greenland (Denmark v. Norway, 1933, PCIJ) — sovereignty over thinly-populated territory needs only a modest continuous display of authority plus the intention to act as sovereign.
• Temple of Preah Vihear (Cambodia v. Thailand, 1962, ICJ) — a State that accepts a boundary map for years without protest is bound by acquiescence/estoppel.

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