Rule Against Perpetuities

A property-law doctrine that invalidates future property interests that might vest only after an unacceptably remote period, traditionally measured by a lifespan test (e.g., lives in being plus a fixed term) to prevent long‑term restrictions on alienability and control by remote beneficiaries.

The Rule Against Perpetuities is a legal doctrine that invalidates certain contingent future interests in property that may vest only at an indeterminate remote time; classically formulated at common law to require that such interests, if they are to vest, must do so within a legally prescribed measuring period (commonly expressed in classical doctrine as 'lives in being plus twenty‑one years'), o