Description: Legal provision enacted in some southern states after the passage of the Fifteenth Amendment that exempted men who could vote before 1866 and their descendants from suffrage restrictions such as literacy tests and poll taxes.
Significance: Until the Supreme Court struck down grandfather clauses as a violation of the Fifteenth Amendment to the U.S. Constitution, states used this as a method to disenfranchise blacks and allow illiterate white men to vote.
The Fifteenth Amendment, adopted in 1870, guaranteed that citizens of the United States could not be denied their right to vote by the federal or state government on account of race, color, or previous condition of servitude. However, many southern states passed laws, including grandfather clauses, designed to disenfranchise African Americans through literacy tests or poll taxes. Guinn v. United States (1915) involved an Oklahoma law that required all voters to prove that they or a direct ancestor could vote before 1866 or to pass a literacy test. The Supreme Court found the grandfather clause to be an unconstitutional evasion of the Fifteenth Amendment. Although the Oklahoma provision did not directly cite race, most white men could prove that an ancestor could vote. Therefore, it was mostly people of color who were forced to take the literacy test. In Lance v. Wilson (1939), the Court ruled that literacy tests were also unconstitutional.