You buy from a Chinese supplier, you sell to a Vietnamese customer, you sign with a Thai partner: if something goes wrong, which law decides? The answer depends on what is written in your contract, and on your partner's country.
For information only, up to date on 1 November 2026, based on the official texts cited at the bottom of the page. For an important contract, get advice.
1. You can choose the law
In the European Union, "a contract shall be governed by the law chosen by the parties" (Rome I Regulation, Article 3). You can choose French law, or even the law of a non-European country (Article 2). Write this choice clearly in the contract.
2. If nothing is written
The Rome I Regulation gives the answer (Article 4):
- Sale of goods: law of the seller's country. If you buy from a Chinese factory without writing anything, it is in principle Chinese law.
- Provision of services: law of the service provider's country.
- Distribution contract: law of the distributor's country.
3. The Vienna Convention (sales of goods between businesses)
For sales of goods between businesses in different countries, a United Nations convention may also apply: the 1980 Vienna Convention (CISG). 97 States apply it. For our countries:
| Country | Applies the Convention? | Good to know |
|---|---|---|
| France | Yes, since 1 January 1988 | — |
| China | Yes, since 1 January 1988 | China made a reservation on one rule of Article 1. |
| Vietnam | Yes, since 1 January 2017 | Everything must be in writing: concluding, changing or ending the contract, the offer and the acceptance. An oral agreement does not count. |
| Thailand | No (not on the official list) | All the more reason to write in the contract which law applies. |
4. What the choice cannot set aside
- "Overriding mandatory provisions": some rules of a country apply whatever the contract says (Article 9).
- Private customers: when a business sells to a consumer in his or her country, the consumer keeps the protection of the law of that country (Article 6).
What to do
- Write in the contract which law applies.
- Also write who will decide a dispute (courts of a country or arbitration): the Rome I Regulation says which law applies, not which court decides.
- With Vietnam: everything in writing, including every change.
- With Thailand: do not rely on the Vienna Convention.
- Keep the signed contract and every written exchange.
Official sources (read on 01/11/2026) : Regulation (EC) No 593/2008 on the law applicable to contractual obligations (Rome I), Art. 2, 3, 4, 6, 9 — EUR-Lex · United Nations (UNCITRAL) — Status of the 1980 Vienna Convention
General information, not legal advice. Check the official source before you decide.