suzerainty

A suzerain (, from Old French "above" + "supreme, chief") is a person, state or polity who has supremacy and dominant influence over the foreign policy and economic relations of another subordinate party or polity, but allows internal autonomy to that subordinate. Where the subordinate polity is called a vassal, vassal state or tributary state, the dominant party is called the suzerain. The rights and obligations of a vassal are called vassalage, and the rights and obligations of a suzerain are called suzerainty.

Suzerainty differs from sovereignty in that the dominant power does not exercise centralized governance over the vassals, allowing tributary states to be technically self-ruling but enjoy only limited independence. Although the situation has existed in a number of historical empires, it is considered difficult to reconcile with 20th- or 21st-century concepts of international law, in which sovereignty is a binary concept, which either exists or does not. While a sovereign state can agree by treaty to become a protectorate of a stronger power, modern international law does not recognise any way of making this relationship compulsory on the weaker power. Suzerainty is a practical, de facto situation, rather than a legal, de jure one.