The Voting Rights Act of 1965 provided direct federal enforcement to remove literacy tests and other devices that had been used to disenfranchise African Americans. It authorized the appointment of federal registrars to register voters and observe elections. It also prevented states from changing voter requirements and gerrymandering districts for a period of five years without federal review. The poll tax, a point of dispute, was fully banned in 1966. The sweeping provisions of the act were greatly due to the persistent diplomacy of Clarence M. Mitchell, Director of the NAACP Washington Bureau, and his associates.