Ab Initio

Lat. From the beginning; from the first act. A party is said to be a trespasser ab initio, an estate to be good ab initio, an agreement or deed to be void ab initio, a marriage to be unlawful ab initio, and the like.

Plowd. 6 a, 16 a. 1 Bl. Com. 440.

The word ab, in this sense, is expressive not only of a point or period of time, but of continuity from that to a subsequent time, without change. Thus, to say a deed or a marriage is void ab initio, is as much as to say, it was void when made, and has never been otherwise. See Trespasser ab initio. At the beginning; at first; originally. Ab here has the sense of in, as denoting merely a separate period of time, without any necessary continuity to a subsequent time; or rather, it is used in connections denoting actual contrast or change. Thus, it is said a gift or conveyance may be valid at the beginning, (ab initio,) that is, when first made, and become invalid by a subsequent act, (ex post facto;) and e converso. Bract. fol.

11 b, 51 a. 2 Bl. Com. 308.

In initio is used in the same sense. Bract. fol.

18 a, 58 a.

So, ab initio, in principio donationis; at the beginning, at the commencement of the gift. Id. fol.

17 b.

So, ab initio, sive post tempus; at the beginning, or afterwards: ab initio, vel ex post facto; at the beginning, or by a subsequent act. Id. fol.

213a.

The phrase has the same sense in the civil law.

Inst. 2. 17. 9. Id. 4. 1. 16.

And in the law maxim, Quod ab initio non valet tractu temporis non convalescet; that which is originally void shall not acquire validity by lapse of time. See Convalescere. It is constantly used by Bracton in contrast with the phrase ex post facto, (q. v.)