forced heirship arises when children or close relatives of a deceased are entitled as of right to a share of the deceased's patrimony (in broad terms, the estate after adding back any lifetime gifts), irrespective of the deceased's wishes. England and common law jurisdictions generally have put very few restrictions on testators, whereas civil law jurisdictions (based on Roman law) require testators to make provision for their immediate family.

In some countries (eg France), forced heirship rules are mandatory in the sense that part of the estate is automatically reserved to the relevant forced heirs, whilst in other countries (eg Germany, Italy and Switzerland) the forced heirs simply have a claim against the beneficiaries under the will.

Which succession laws apply will be decided differently by different jurisdictions depending on the connecting factor accepted and used by that jurisdiction. Which connecting factor that applies is a matter for the conflict of laws or private international law rules of that particular jurisdiction. For information on English private international law rules, see the Private