Grandfather Clause

A grandfather clause is a situation in which an old rule continues to apply to some existing situations, while a new rule will apply to all future situations. Frequently, the exemption is limited; it may extend for a set period of time, or it may be lost under certain circumstances. For example, a "grandfathered power plant" might be exempt from new, more restrictive pollution laws, but those rules would not apply if the plant were expanded. Often, such a provision is used as a compromise or out of practicality, to effect new rules without upsetting a well-established logistical or political situation. This extends the idea of a rule not being retroactively applied.

The concept originated in late nineteenth-century legislation and constitutional amendments passed by a number of U.S. Southern states, which created new literacy and property restrictions on voting, but exempted those whose ancestors (grandfathers) had the right to vote before the Civil War. The intent and effect of such rules was to prevent poor and illiterate African American former slaves and their descendants from voting, but without denying poor and illiterate whites the right to vote. Although these original grandfather clauses were eventually ruled unconstitutional, the terms grandfather clause and grandfather remain in use, with no connotation regarding the justness of these provisions when applied in other areas.