Several years ago we ran an article on ex post facto laws – laws that become effective retroactively. In general, such laws are unconstitutional and therefore unenforceable.
The effective date of a law (or a change in a law) can be of monumental significance. For example, a law raising the age to obtain a driver’s license from 16 to 17 could affect tens of thousands of 16 year olds, many of whom might have jobs dependent upon being able to drive.
What if you were 16 years and one day old on the effective date of such a change? On the day you became 16 you had the right to apply for a driver’s license. Did you lose that right? No. As an outgrowth of the prohibition against ex post facto laws, the concept of “grandfathering” protects vested rights which might otherwise be adversely affected by the new law. If a right existed and was sufficiently vested under prior law it cannot be reduced or eliminated under a new law.
Next time you see your grandfather, think “ex post facto” – after the fact.
– BBC&B