Cross-border · For advisers · Information, not legal advice — as at 19 June 2026
Foreign-law certificates explained
When an estate crosses two legal systems, the authorities in one country often need formal proof of what the other country’s law says. That proof is a “certificate of law” (or affidavit of law) — a signed legal statement from a lawyer qualified in the relevant law. You typically need one when a foreign will has to be acted on abroad, or when a foreign court or registry needs to apply another country’s succession rules.
Why a certificate is needed at all
A notary in Lisbon is an expert in Portuguese law — not English law. A probate registry in England applies English procedure — it doesn’t know French or Italian succession rules. So when an estate touches two systems, the authority dealing with it needs someone qualified to state, formally and reliably, what the other country’s law provides — for example, that an English will is valid, or who inherits under it, or what a Spanish reserved share amounts to. That signed statement is the certificate (or affidavit) of law.
The two directions it runs
- Outbound — a Certificate of English Law for a foreign notary. When someone with an English will owns property in Portugal, Spain, Italy or France, the local notary needs to be told, in their own language, that the will is valid and who inherits under it. A Certificate of English Law does that, so the local transfer can proceed.
- Inbound — a certificate of foreign law for a home-country forum. When someone who lived in Portugal, Spain, Italy or France leaves assets in the UK, the England & Wales Probate Registry (and similar forums elsewhere) may need formal proof of that country’s succession law before issuing a grant. A certificate of Portuguese (or Spanish, Italian, French) law supplies it.
A related document, the expert-witness opinion, is the contested-case version — a neutral expert’s statement of foreign law where heirs are in dispute before a court.
Who can sign one
This is the key point: the certificate should come from someone properly qualified in the law being proved — in practice, a lawyer of that country — not in the law of the country receiving it. The real advantage is when one person is qualified in both: they understand the home-country will and are the regulated local lawyer who acts on it, so the certificate is produced in-house, in the right language, ready to file — without the outsourcing, sworn translation and delay a referral chain adds. (See how we work — and who does your work.)
That dual grounding is real here. Your work is signed personally by Colin Carroll, who first qualified as an Irish and English solicitor — and so understands the English and Irish probate process — before moving to live and practise on the continent as a registered European lawyer under EU Directive 98/5/EC, at home in the civil-law succession systems of Portugal, Spain, Italy and France, where he is registered with the Ordem dos Advogados, the Ilustre Colegio de Abogados, the Ordine degli Avvocati and the Ordre des avocats — with professional-indemnity insurance in each.
When you’ll come across one
- A British family settling a relative’s Portuguese flat (Certificate of English Law for the notary).
- A UK solicitor administering the estate of someone who had retired to Spain but kept UK bank accounts (certificate of Spanish law for the grant).
- A Portuguese estate where the deceased left a will made abroad and in another language — a French or Italian will, say — that the Portuguese notary must give effect to. Here a certificate of that law confirms the will’s validity and what it means.
- Heirs disputing a French entitlement before a court (expert-witness opinion).
It’s worth being clear that this is not the same as translation. Translating a foreign will tells the authority what it says; the certificate tells them what the law makes of it — whether it is valid and how it operates. The two are separate pieces of work (and, where both are needed, separate items on the bill). If any of these is you — or your client — the certificate is usually a discrete, fixed-fee piece of work.