Rule against perpetuities is aimed at the control of future interests in property, especially real property. It prohibits the grant of an estate where the persons entitled to inherit a future interest cannot be determined with absolute certainty within 21 years after the death of someone alive when the interest was created. In other words, in order to transfer a future interest in property, the transfer must be guaranteed to take place within 21 years after the death of a certain living person. For example, if the transfer is dependent on a future marriage of a child born to a living person, this might violate the rule since there is no certainty that the child will be born or will marry within that time.
To avoid invalidation under the rule, it is common practice to put "savings clauses" in instruments. These clauses basically state that if the interest created should be deemed to violate the rule against perpetuities it shall terminate one day before twenty-one years after the last life in being has passed. Recently, there has been movement to simplify the rule against perpetuities and/or "repeal" it. Section 2-901 of the Uniform Probate Code (1990) sets forth the simplification approach. Under the provisions of the UPC, a non-vested property interest is invalid unless (i) it is certain to vest or terminate no less than twenty-one years after a life in being or (ii) "the interest either vests or terminates within 90 years after its creation."
