Grandfather Clause/Trivia

The name has a rather unfortunate origin with the "Jim Crow laws" (named after a "minstrel" character) that enforced segregation in the southern USA after the Civil War. Though they were designed to prevent newly freed slaves from voting, the laws couldn't be written to flat-out say, "Black people can't vote." So state legislatures enacted poll taxes and literacy tests, which succeeded in disqualifying black voters, who were overwhelmingly poor and illiterate. However, many white farmers were also poor and illiterate, meaning the Jim Crow laws affected them as well. In response, the legislatures changed the laws to, effectively, guarantee that anyone whose grandfather had been able to vote could himself vote without paying the tax or proving literacy. As the grandfathers of most black farmers were slaves and thus unable to vote, this served as an effective measure for disenfranchising African-Americans without hurting poor whites.

In more recent times, a grandfather clause can come into effect when any sort of laws are altered or updated, so that existing buildings, tenants or procedures are not affected. For example, when a realty company changes their regulations regarding pets, it's common to allow anyone who already had one to keep them, and simply disallow new pets.