Any
clause in a
law which makes an exception for people or things if, when the law was passed, they were already doing whatever is being forbidden. And related concepts.
Building codes often grant exceptions for buildings built before the code was enacted, for example.
The phrase comes from a series of similar changes in the
constitutions of six
southern US states between
1895 and
1910. The right to vote was limited to
literate people with some arbitrary amount of wealth, but exceptions were made for people who'd had the right to vote during the
Civil War, or whose
ancestors had had that right at the time. By chance, quite
coincidentally, the set of people allowed to vote in those states during the
Civil War was the set of all
white people in those states, and both
poverty and
illiteracy were depressingly common among
black and
white people both. The effect, perhaps unintentional, was to limit the
franchise to most whites (not counting poor,
illiterate immigrants) and a minority of blacks.
The
United States Supreme Court took one look at this in
1915, rolled its collective eye, and told them to go home and let everybody vote. Other equally unfortunate
coincidences followed, and things didn't really get set right until the
1960s. I've read that there are counties in
the South to this day where some odd arrangements are in place, but it does seem that
coincidences are a lot less common than they once were.
Note that nobody,
North or
South, let
chicks vote at all back then, before we of the harsh vowels up here start patting ourselves on the back too much.