Loss of State Territory

In one line

Territory is lost in the same five ways it is gained, seen from the other side, plus two that have no counterpart: abandonment, and the emergence of a new State.

In the wording a student can write in an exam: a State loses territory by cession, by another State's prescription, by the operation of natural forces, by revolt resulting in the emergence of a new State or in secession, and formerly by conquest, which is no longer lawful. It may also lose territory by abandonment or dereliction, which requires both the physical abandonment of the territory and the intention to relinquish sovereignty.

The modes

Cession

The mirror of acquisition by cession: the transferor loses what the transferee gains, by agreement.

This is the mode that raises a live constitutional question in India, and it is dealt with in its own section below.

Prescription by another State

The mirror of acquisition by prescription. A State loses territory when another exercises sovereignty over it publicly, peacefully and for long enough, with the acquiescence of the first.

The practical lesson from [Acquisition of State Territory] is the same seen backwards: a State that wishes not to lose territory must protest, and keep protesting, because protest is what prevents the other State's possession from being peaceful.

The Island of Palmas award is again the authority, and its proposition is a warning: effectiveness is required not only for the act of acquisition but equally for the maintenance of the right. A State that stops exercising authority over an outlying territory is not merely idle; it is losing.

Operation of nature

The mirror of accretion. A river erodes one bank and deposits on the other, an island disappears, the sea takes land.

Gradual accretion moves a river boundary; sudden avulsion does not. Rising sea levels raise a question the law has not settled: whether a State whose territory is submerged ceases to exist, and whether its maritime zones survive the loss of the land that generated them. There is no rule, and saying so is the correct answer.

Revolt, secession and independence

A State loses territory when part of it becomes a new State. That may happen with the parent State's consent, as with the grant of independence, or against its will, as with a successful secession.

There is no general right to secede in international law. Self-determination, one of the seven principles of Resolution 2625, is not a licence to break up existing States: the same Declaration provides that nothing in it authorises or encourages any action which would dismember or impair, totally or in part, the territorial integrity or political unity of sovereign and independent States conducting themselves in compliance with the principle of equal rights and self-determination of peoples and thus possessed of a government representing the whole people belonging to the territory without distinction as to race, creed or colour. So self-determination outside the colonial context is generally satisfied within the existing State rather than by leaving it.