Illustrations of the rule against perpetuities

The fertile octogenarian is a fictitious character that comes up when applying the rule against perpetuities. The rule presumes that anyone, even an octogenarian (i.e., someone between 80 and 90 years of age) can parent a child, regardless of sex or health.[1] For instance, suppose that a will devises a piece of land known as Blackacre "to A for her life, and then to the first of A's children to reach 25 years of age." A is, at the time the will is probated, an 85-year-old woman. In applying the rule against perpetuities, an imaginative lawyer will argue (and a court must accept under the common law rule itself) that A could have a child in her 86th year and then in her 87th year all of A's other children could die, then in her 88th year A herself could die. Because the interest will not vest until her new child reaches 25 years of age, which cannot happen until more than 21 years after A and her other children (together who form the "lives in being" to which the rule refers) have all died, the rule against perpetuities makes the entire gift "to the first of A's children to reach 25 years of age" void. A will hold Blackacre for life, and then the property will revert to the person whose will transferred it to A in the first place. (Actually, it will go to that person's estate, since the will was probated only after his death.)

While it is true that there is often no statutory maximum age limit to perform an adoption, and adopted children are often treated the same as natural children, so an 86-year-old woman who adopts a newborn child is legally in the same position as an 86-year-old woman who gives birth, the fertile octogenarian rule predates the laws allowing legal adoption.

The legal fiction of the fertile octogenarian assumes that a living person, regardless of sex, age, or physical condition, will always be capable of having more children, thus allowing an interest to vest 21 years after all the lives in being at the time of the grant are dead. Couples have been known to marry in their late eighties.[2]

In certain places this assumption will be limited to a fixed age set by statute. Furthermore, many jurisdictions have discarded old common-law fictions such as the "fertile octogenarian."

A related legal fiction, which assumes that a living person is fertile at birth, is known as the precocious toddler.

The problem of the unborn widow is a frequently used illustration of the odd outcomes of the traditional rule against perpetuities.[3] The unborn widow rule prohibits an unidentified widow from being treated as a validating life.[4][5] If, for example, a grantor's will devised land "to my son, for life; then to his wife [or widow], for life; then to his children living at the time of her death," the children's contingent remainder (contingent on their status as "living" at the time of the widow's death) would be invalid, even if the grantor's son was an elderly and already-married man.[3] Regardless of the age of the grantor's son, he could leave or lose by death his current wife and subsequently marry another woman who was not-yet-born at the time of conveyance; thus the widow that survived him would not be, with certainty, a life in being at the time of conveyance.[5]

The rule against perpetuities voids the interest to B's children then living. (However, if the phrase then living is removed, the interest would vest immediately upon B's death because both his widow and all his children would be identifiable at that time.)

Other hypothetically relevant possibilities which almost never actually occur but have been invoked by lawyers or courts to invalidate transfers under the rule against perpetuities include the slothful executor (a situation where the executor of the estate does not probate the will for many years after the testator's death), the magic gravel pit (a transfer to be made as soon as a gravel pit is out of gravel may not vest for hundreds of years), the war that never ends (a transfer to be made at the end of a war might never happen), and other similar situations.

Because these hypothetical scenarios show how a reasonable gift can be voided based on so unlikely an outcome, they have generated much criticism among legal scholars, resulting in the abrogation of the rule against perpetuities by statute in many jurisdictions. Many U.S. States have adopted laws mollifying the application of the rule by requiring courts to "wait and see" for a period of years, sometimes as long as 360 years (which effectively negates the possibility of litigation ensuing during the life of any person alive at the same time of the author of the will).

Some jurisdictions have ameliorated specific problems of the rule by creating statutory presumptions to counter those problems. Under such statutes, for example, a woman is presumed to no longer be fertile after a particular age (typically 55), and a gift to a person's widow or widower is presumed to vest in whoever was that person's spouse at the time of the gift.

These rules have also long been a target of legal humorists.