Latin. The making of a will. The power of making a testament, or of acquiring under a testament made by another. Under the civil law, this was a power at one time vested only in the Roman citizen, although it became more general in the time of Justinian. The testamenti factio was necessary to any participation whatever in a testament. No one could test without it, nor could a legatee benefit by the legacy bequeathed to him unless he had this power. Every testamentary tutor appointed by the testator required to have the testamenti factio, or their appointment was void. In Scotland, prior to the passing of the Act 6 Will. IV. c. 22, a bastard dying without lawful issue, had no testamenti factio, and his property passed to the Crown; but, by that Statute, such persons were empowered to dispose of their movables by testament in the same manner as others. In Scotch law, this phrase can only signify the power of making a will, as any one may be a beneficiary under another's settlement.