Forced heirship is a rule of succession law that reserves fixed shares of a person's estate for specific relatives, usually children and spouses, regardless of what the will says. In France, children collectively have an untouchable claim to half or more of a parent's estate. Similar regimes apply across most of continental Europe, Latin America, Japan, and, in the form of Islamic succession rules, much of the Middle East. Common law countries like the US and UK take the opposite approach: testamentary freedom, with narrow exceptions.
For internationally mobile families, forced heirship creates real planning problems. An entrepreneur who wants to leave a business to the child who runs it, provide for a second spouse, or exclude an estranged relative may find their home country's civil code overriding every document they sign. The rules often follow nationality or domicile, not residence, so moving does not always escape them.
This is precisely what offshore firewall provisions exist to counter. Statutes in the BVI, Cayman, Jersey, Guernsey, and the Cook Islands provide that questions about a local trust are decided exclusively under local law, and that foreign judgments based on forced heirship rights will not be enforced against trust assets. Panama's foundation law contains the same rule. Assets transferred to such a structure during the settlor's lifetime generally sit outside the estate the home country's succession code can reach.
The usual caveats apply: transfers must be completed while the settlor is alive and well-advised, home courts may still exert pressure on heirs or assets located within their reach, and anyone planning around heirship rules needs counsel in both jurisdictions.
Related terms: settlor, trust deed, discretionary trust.