The United States' Supreme Court has ordered the Government to reimburse Native American tribes for the costs of providing public services including education, environmental protection and security. For several years, the Congress failed to allocate sufficient money, depriving the tribes hundreds of millions of dollars. Under Federal laws which allow the tribes to manage their own affairs, the Government must repay them for running such programmes. It is a major victory for Navajo Indians and a number of other tribes. But the decision also has implications for contractors in general.