- Common-law jurisdictions (the UK, most of the US, much of the Commonwealth) generally follow testamentary freedom, you can leave your estate to whoever you want, subject to limited claims from dependents in some places.
- Civil-law jurisdictions (France, most of continental Europe, much of Latin America) apply forced heirship, a fixed portion of the estate, the réserve héréditaire or its equivalent, is reserved by law for children and sometimes a spouse, regardless of what the will says. In France, for example, the reserved portion scales with the number of children, up to three-quarters of the estate can be protected from disinheritance depending on how many children there are. A will drafted under common-law assumptions, disinheriting a child or leaving everything to a second spouse, can be perfectly valid where it was written and still be overridden, in whole or in significant part, the moment it touches an asset located in, or an heir resident in, a forced-heirship jurisdiction.
Where the Conflict Actually Plays Out: Situs Rules
Most jurisdictions decide which succession law applies to an asset using one of two approaches:
- Unity of succession, one law (usually the deceased's nationality, domicile, or habitual residence at death) governs the whole estate, wherever the assets sit. The EU Succession Regulation (Brussels IV), which most EU member states apply, works this way, habitual residence at death generally governs, unless the deceased chose their nationality's law in the will.
- Scission, different laws govern different assets depending on where they're located. Movable property (bank accounts, securities, most business interests) is often governed by the deceased's domicile; immovable property (real estate) is very often governed by the law of the country where the property physically sits, full stop, regardless of the deceased's domicile or nationality. This is where three-jurisdiction estates get genuinely messy. A US-domiciled individual with a French holiday home can generally choose US law to govern their worldwide estate under Brussels IV's nationality-election provision, but that election has to be made explicitly in the will, in the right form, and some French notaries and courts have still required the reserved heirs' portion to be respected in practice for the French real estate, particularly where heirs are French-resident and contest the election. The gap between what the regulation technically allows and what actually survives a contest in a local court is where families lose money and years.
The Three Places Wills Most Often Collide
-
Multiple wills covering overlapping assets. Families are frequently advised to have a separate will in each jurisdiction where they hold significant assets, a reasonable idea in principle, since a local will speeds up local probate. The failure mode is drafting each will independently, without a revocation clause carefully scoped to that jurisdiction only. A later will's general revocation clause ("I revoke all previous wills") can accidentally cancel an earlier will made for a different country's assets, leaving that jurisdiction's assets to pass under intestacy rules instead of the plan the family thought was in place.
-
Matrimonial property regime colliding with the will. Civil-law jurisdictions often apply a default matrimonial property regime (community of property, or a variant) that determines what's actually in the estate before succession law even applies to distribute it. A couple who married in a community-property jurisdiction and later moved to a common-law country may find, at death, that half the "estate" the will purports to distribute never belonged solely to the deceased in the first place, the surviving spouse already owned it outright under the marital regime.
-
Trust and foundation assets treated as still part of the estate. Some civil-law jurisdictions with strong forced heirship rules apply "clawback" doctrines that pull lifetime gifts, and in some cases trust-settled assets, back into the estate calculation for the purpose of assessing whether reserved heirs got their mandated share, even when the trust itself is validly recognized. This is a frequent, unpleasant surprise for families who assumed a trust settled decades earlier had permanently removed those assets from succession exposure.
What Actually Reduces the Conflict
-
An explicit, correctly executed choice-of-law election, where the relevant regulation allows it (Brussels IV is the clearest example), naming the law of nationality to govern the worldwide estate, done in the specific form each jurisdiction's law requires, not just stated informally.
-
Jurisdiction-scoped wills with narrow, explicit revocation clauses, each will should state precisely which assets or which country's assets it covers, and should revoke only prior wills covering the same scope, not "all previous wills" as a blanket phrase.
-
A pre-death review of the marital property regime actually in effect, not the one the couple assumes applies based on where they currently live, this can change automatically when a couple relocates, depending on the jurisdictions involved.
-
Coordination between local counsel in each relevant jurisdiction, not a single advisor drafting documents for countries they don't practice in. Forced heirship, clawback rules, and situs classification are exactly the kind of detail that varies enough between neighboring countries that general international experience isn't a substitute for jurisdiction-specific counsel reviewing the final documents.
The Cost of Getting This Wrong
The dispute that actually happens is rarely "the will was invalid." It's a validly executed will in Jurisdiction A running into a forced heirship claim in Jurisdiction B, contested by an heir who has standing there, resolved years later through litigation that consumes a meaningful share of the very assets in dispute, while the family's actual wishes sit in a document that a court somewhere has decided doesn't fully apply.
For any family with meaningful assets in more than one legal tradition, the planning question isn't whether there's a will. It's whether the jurisdictions that can actually reach those assets at death have been checked against each other, and that check needs redoing any time residence, domicile, marital status, or major asset location changes.
