CATONIANA REGULA. In Roman law. The rule which is commonly expressed in the maxim, Quod ab initio non valet tractu temporis non convalebit, meaning that what is at the beginning void by reason of some technica) (or other) legal defect will not become valid merely by length of time. The rule applied to the institution of haAredes, the bequest of legacies, and such like. The rule is not without its application also in English law; e. g., a married woman’s will (being void when made) is not made valid merely because she lives to become a widow. Brown.