Acquisition of State Territory

In one line

There are five classical ways a State can acquire territory and a sixth that international law has abolished, and the one that decides most real disputes is effective control over time.

In the wording a student can write in an exam: the traditional modes of acquiring territory are occupation, prescription, cession, accretion and conquest or subjugation, to which plebiscite and adjudication are sometimes added. Conquest is no longer a lawful mode, since article 2(4) of the Charter prohibits the threat or use of force and Resolution 2625 provides that no territorial acquisition resulting from the threat or use of force shall be recognised as legal. In practice most disputes are decided not by classifying the mode but by asking which State has exercised the functions of a State continuously and peacefully, which is the test in the Island of Palmas case.

Why the classical list is borrowed from property law

The five modes come from Roman law's rules for acquiring things: occupatio, praescriptio, cessio, accessio and conquest. Publicists of the seventeenth and eighteenth centuries applied them to States because States were then thought of as the property of sovereigns, and the vocabulary stuck.

The borrowing has consequences worth knowing. It makes the law of territory look tidier than it is; it produces categories that overlap in practice; and it is why tribunals now prefer to ask about the display of State authority rather than to sort a claim into a box. A good answer gives the classical list, because that is what the question asks, and then says this.

The modes

Occupation

The acquisition of terra nullius, territory belonging to no State, by taking possession of it with the intention of acquiring sovereignty.

Two elements: the intention to act as sovereign, and the actual exercise of authority. Discovery alone is not enough, and this is the proposition Palmas settled.

Facts. Island of Palmas Case (Netherlands v. United States), (1928) 2 RIAA 829, award of Max Huber as sole arbitrator, 4 April 1928. The Island of Palmas, also called Miangas, lies between the Philippines and what was then the Netherlands East Indies. The United States claimed it as successor to Spain under the Treaty of Paris of 1898, Spain's title resting on discovery in the sixteenth century. The Netherlands claimed on the basis of a long and continuous exercise of State authority through arrangements with the island's local rulers.

Held. The island belonged to the Netherlands. The continuous and peaceful display of territorial sovereignty, peaceful in relation to other States, is as good as a title, and is a constituent element of territorial sovereignty; effectiveness is required not only for the act of acquisition but equally for the maintenance of the right. Discovery alone, without any subsequent act, cannot at the present time suffice to prove sovereignty. If discovery is treated as creating an inchoate title, that title must be completed within a reasonable period by effective occupation, and an inchoate title cannot prevail over another State's continuous and peaceful display of authority. The arbitrator also applied intertemporal law: a juridical fact must be appreciated in the light of the law contemporary with it, but the continued existence of a right must satisfy the conditions required by the evolution of the law.