In Roman law. The rule which is commonly expressed in the maxim, Quod a6 initio non valet tractu iemporis non convalebit, meaning that what is at the beginning void by reason of some technical (or other) legal defect will not become valid merely by length of time. The rule applied to the institution of hccredes, the bequest of legacies, and such like. The rule is not without its application also in English law; e.