Forced heirship is generally a feature of civil-law legal systems which do not recognize total freedom of testation, in contrast with common law jurisdictions.
Critics suggest that there is a great difference between varying wills to the minimum degree to provide sufficient financial support for dependants, and prohibiting the testator from distributing the estate or a proportion of the estate to any female children, or younger male children, and that it cannot be any less repugnant to force a deceased person to distribute their assets in a certain manner on their death than it would be to tell them how they may do so during their lifetime.
Realty, or heritable property, on the other hand, was originally inherited in joint tenancy, termed gavelkind, and passed on to the kin group as a whole.
However, after the household superseded the kin group in importance in the late Middle Ages, preference was given to the deceased's immediate family, specifically any surviving sons, and none could be favored over his siblings.
However, gavelkind inheritance gave rise to inter-family rivalries, so primogeniture laws arose in some areas of feudal Europe giving preference to the eldest son in order to stem feuding.
The terce was earliest known as tertia collaborationis and first appears in the Ripuarian law code, making it also a localized Germanic custom.
In Louisiana, Civil Code article 1493 stipulates that "Forced heirs are descendants of the first degree who, at the time of the death of the decedent, are twenty-three years of age or younger or descendants of the first degree of any age who, because of mental incapacity or physical infirmity, are permanently incapable of taking care of their persons or administering their estates at the time of the death of the decedent".
Forced heirs may demand collation, whereby certain gifts received by any successor in the three years before the death of the parent may be subtracted from their share.