However, tribes frequently collaborate and cooperate with states through compacts, contracts, or other agreements. The State-Tribal relationship is also one of a government to a government. The relationship between the tribes and the United States is one of a government to a government. This principle has shaped the entire history of dealings between the federal government and the tribes, and is lodged in the Constitution of the United States. Tribes possess all powers of government except those which Congress has expressly extinguished or which the Supreme Court has ruled are inconsistent with overriding national interests.
Tribes have the inherent right to operate under their own governmental systems.
Many have adopted constitutions, while others operate under Articles of Association or other bodies of law, and some still have traditional systems of government. The chief executive of a tribe is generally called the tribal chairperson, but may also be called principal chief, governor, or president. The chief executive usually presides over what is typically called the tribal council. The tribal council performs the legislative function for the tribe, although some tribes require a referendum of the membership to enact laws. A federally recognized tribe is one that was in existence, or evolved as a successor to a tribe at the time of original contact with non-Indians.