Encyclopaedia Britannica: The clause "provided that those who had enjoyed the right to vote prior to 1866 or 1867, and their lineal descendants, would be exempt from recently enacted educational, property, or tax requirements for voting. Because the former slaves had not been granted the franchise until the adoption of the Fifteenth Amendment in 1870, those clauses worked effectively to exclude black people from the vote but assured the franchise to many impoverished and illiterate whites." The clause was declared to be unconstitutional in 1915, but was not finally overwritten until 1965. Actual legislation to prevent mixed marriages was passed in other countries but was excluded in the USA. The Voting Rights Act was the federal legislation passed to overwrite the effects of various Jim Crow laws and the Grandfather clauses. The Eight Box Law of 1882 was designed to achieve the same result as a Grandfather clause but was only successful (and it was) if voting procedures were manipulated and misused on the day.