The Warren Court unanimously upheld the constitutionality of the Voting Rights Act in South Carolina v. Katzenbach (1966). The Act suspended the use of literacy tests, which were designed to keep African Americans from voting. The Act also provided for the placement of federal examiners to ensure that states did not engage in voting discrimination. Several states gave alternative tests to illiterate whites to ensure their right to vote. South Carolina—supported by Alabama, Georgia, Louisiana, Mississippi, and Virginia—had challenged the constitutionality of various provisions of the Voting Rights Act. The Court, in an opinion written by Chief Justice Earl Warren, found that Congress had the power under Section 2 of the Fifteenth Amendment, which protects the right to vote, to pass laws prohibiting voting discrimination.