Not to be confused with sovereignty.
Suzerainty (/ˈsjuːzərənti/, /ˈsjuːzərɛnti/ and /ˈsjuːzrənti/) is any relationship in which one region or nation controls the foreign policy and international relations of a tributary state, while allowing the tributary nation to have internal autonomy.
Suzerainty differs from true sovereignty in that, though the tributary state or person is technically independent and enjoys self-rule, in practice this self-rule is limited. 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 either exists or does not. While a sovereign nation 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, therefore, is a practical, de facto situation, rather than a legal, de jure one.