The UN Trusteeship System was built upon the premises of Mandate administration. It was specifically designed to further self-government and decolonisation. Moreover, it operated mainly on the principle of state-based administration.

At the same time, the Trusteeship System administration shared some more parallels with modern engagements in international territorial administration than the Mandate System. The Trusteeship system gave rise to two quasi-experiments of direct UN administration: the proposed UN administration of Jerusalem and de jure authority of the UN over Namibia - two examples of direct UN administration exercised after the termination of former Mandates (the UK Mandate over Palestine and South Africa's Mandate concerning South West Africa). Furthermore, the Trusteeship System corrected some of the failings of the League's system of administration and laid some foundations for the conceptualisation of territorial administration under the umbrella of peace-maintenance.

Genesis

The Trusteeship System has its origins in the negotiations held during World War II. Both the US and the Soviet Union pushed for the dismemberment of the old European empires, and organised bilateral talks on the issue of decolonisation as early as 1942. The first proposal to establish an international forum for the control of colonial policy was prepared by the US Department of State. The draft, known as the “Declaration by the United Nations on National Independence”, proposed the creation of a truly international trusteeship administration, composed of UN representatives, interested nations and the trust territories, which would operate through regional Councils in order to supervise the protection of colonial territories.