retrocession

Retrocession is the act of returning sovereignty, jurisdiction, or property from one state or authority to a former holder after it was ceded or transferred. In international law and diplomacy, retrocession describes the reversal of a previous cession, typically through treaty, plebiscite, or other formal agreement. The term can apply to territory, legal jurisdiction, concessions, or other rights and privileges that were once ceded and later returned.

Territorial retrocession occurs when control over land is restored to the former sovereign, often after treaties, peace settlements, or plebiscites. Retrocession of rights or jurisdiction involves restoring legal authority, regulatory power, or concessions that had been ceded. The exact terms, including any compensation or transitional arrangements, are usually set out in the governing instrument and require the consent of the relevant parties.

Notable examples include the 1920 retrocession of Northern Schleswig to Denmark following plebiscites under the post–World War I settlement, and the return of the Saar region to Germany in 1935 after the end of League of Nations administration and a national referendum. Other instances occur in decolonization and territorial settlements, where territories or rights are restored to the former sovereign or returning state. In international law, retrocession is distinct from cession (a transfer to a new holder) and from restitution or reversion arising from other legal remedies.