The Uniform Law Commissioners promulgated the Uniform Statutory Rule Against Perpetuities in 1986. The perpetuity-reform efforts of the American Law Institute in the Restatement (Second) inspired the Uniform Act. The Restatement and the Uniform Act employ the so-called wait-and-see approach to perpetuity reform. Wait-and-see is a two-step strategy. Step One preserves the validating side of the common-law Rule Against Perpetuities (the common-law Rule): By satisfying the common-law Rule, a nonvested future interest in property is valid at the moment of its creation. Step Two is a salvage strategy for future interests that would have been invalid at common law: Rather than invalidating such interests at creation, wait-and-see allows a period of time, called the waiting period, for the contingencies to work out harmlessly. Although the traditional method of measuring the waiting period is by reference to the period of lives in being at the creation of the interest (the measuring lives) plus 21 years, there are various difficulties and costs associated with identifying and tracing a set of actual measuring lives to see which one is the survivor and when he or she dies. Consequently, in a step the framers of a Restatement of the Law of Property could not appropriately have taken in the early 1980s, given the constraint of basing their position on existing law, the framers of the Uniform Act decided to forgo the use of actual measuring lives and use instead an allowable waiting period of a flat 90 years. The framers intended the 90 years to represent a reasonable approximation of the average period of time reached when actual measuring lives are used. The Uniform Act has been endorsed by the House of Delegates of the American Bar Association (on the recommendation of the Council of the A.B.A. Section of Real Property, Probate and Trust Law), the Board of Regents of the American College of Probate Counsel, and the Board of Governors of the American College of Real Estate Lawyers. It has been enacted, so far, in three states and appears to be on its way toward enactment in several others.
Waggoner, Lawrence W. "The Uniform Statutory Rule Against Perpetuities: The Rationale of the 90-Year Waiting Period." Cornell L. Rev. 73 (1990): 157-69.