<P> The common law rule against perpetuities forbids instruments (contracts, wills, and so forth) from tying up property for too long a time beyond the lives of people living at the time the instrument was written . For instance, willing property to one's great - great - great - great grandchildren (to be held in trust for them, but not fully owned, by the intervening generations) would normally violate the rule against perpetuities . The law is applied differently or not at all, and even contravened, in various jurisdictions and circumstances . </P> <P> Stated more formally, the common law rule against perpetuities forbids some future interests (traditionally contingent remainders and executory interests) that may not vest within the time permitted; the rule "limits the ability of a decedent to exercise dead hand control over property, which the state wishes to be alienable . In essence, the rule prevents a person from putting qualifications and criteria in his / her will that will continue to control or affect the distribution of assets long after he or she has died, a concept often referred to as control by the "dead hand" or "mortmain". </P>

Who is the measuring life in rule against perpetuities