Grandfather clauses were designed to prevent poor and illiterate African Americans from voting.
This term was coined in the 19th century when new rules for literacy tests, poll taxes and requirements for voting were established.
Some white people who did not fulfill the requirements were still allowed to vote because their ancestors ( grandfathers ) had the right to vote. This was a way to make voting possible for white Americans, and to make voting almost impossible for black people.
Today, this term applies to a provision in which an old rule continues to apply to some existing situation while a new rule will apply to future cases.
