Grandfather clause(redirected from Grandfather rule)
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A clause in a new law, regulation, or anything else that exempts certain persons or businesses from abiding by it. For example, suppose a country passes a law stating that it is illegal to own a cat. A grandfather clause would allow persons who already own cats to continue to keep them, but would prevent people who do not own cats from buying them. Grandfather clauses are controversial, but they are also relatively common.