The Rule Against Perpetuities is the principle that no clause in a conveyance, be it a deed or a will or whatever, is valid unless it vests within the life of someone currently living plus twenty-one years, measured from time of conveyance (date of sale, death of testator, etc.). If, under some circumstance, you might not be able to figure out who gets the property by that time, just strike it out as if it wasn't written. It is somewhat complicated, and most lawyers can't remember it a few days after the bar exam. I wish I had had this to carry into my final exam in Real Property:
