There are different ways for states to (attempt to) acquire new territory. Cession is a mode of acquiring territory, whereby one state voluntarily transfers sovereignty over a portion of its territory to another state. This transfer usually takes place by treaty and is most often effected through purchase or formal agreement.

A classic example is the United States’ purchase of Alaska from Russia in 1867, as well as the United States’ purchase of the Danish West Indies from Denmark in 1917. Beyond bilateral agreements of this kind, cession was one of the primary methods of colonisation employed by European powers in Africa and Asia during the nineteenth and early twentieth centuries.

Cession may also occur in the context of resolving border disputes between states, where so-called “land swaps” are agreed to stabilise territorial boundaries. Such mechanisms are often discussed in contemporary peace negotiations – some law professors suggest that a potential future final settlement between Israel and Palestine might involve some form of reciprocal cession of land.

The legal foundations of cession are governed by principles akin to those of contract law:

• No greater rights than the ceding state: The acquiring state cannot obtain a stronger or broader title to the territory than that which the ceding state itself possessed.
• Respect for third-party rights: The acquiring state must honour the potential legal rights of third states in relation to the ceded territory.
• Self-determination: In the modern era, any attempted purchase or transfer of territory must take account of the evolution of international law recognising the right of peoples to self-determination, a principle which limits the ability of states to dispose of territory without consideration for its inhabitants.