South Carolina v. Katzenbach

Passed by Congress in 1965, the Voting Rights Act gave black voters additional guarantees against discriminatory practices. The Fifteenth Amendment of 1870 prohibited the denial of any citizens' right to vote because of " . . . race, color, or previous condition of servitude." The Twenty-fourth Amendment of 1964, prohibited the requirement of a poll tax or any other tax to vote in a federal election.

In spite of these two constitutional amendments, by the 1964 presidential election it became apparent that black voters continued having difficulties in some areas when attempting to register to vote. Martin Luther King, Jr. brought this issue to the forefront of American awareness after he orchestrated a march from Selma to Montgomery, Alabama. President Lyndon B. Johnson quickly authored the Voting Rights Act, which Congress ratified.

In addition to the prohibition of discrimination against blacks, the Voting Rights Act also gives the U.S. attorney general the power to send federal registrars into problem areas. These registrars are authorized to register black voters, ensure that they are allowed to vote, and make sure their votes are properly tallied. The act was readopted in 1970, 1975, 1985, and can be extended by Congress.