Foreign-language documents in Thai court proceedings — translation, certification and filing

The Civil Procedure Code requires foreign-language documentary evidence to be accompanied by a Thai translation, and the court may order the translation certified. The opposing party can challenge the translation, so use a translator who is prepared to testify to it if needed.

Foreign public documents such as company registers or birth certificates usually need authentication by the issuing authority and the Thai embassy in that country, until the Apostille Convention enters into force for Thailand on 28 February 2027.

The Electronic Transactions Act gives legal effect to electronic data, but evidential weight depends on how reliably the data was created, stored and presented. Keeping original files with their metadata is stronger than printed screenshots alone.

Start by asking whether the document is public or private. A foreign public document usually needs certification by the issuing authority, that country’s foreign ministry and a Thai embassy or consulate. Private documents, such as contracts or statements, usually need to be signed before a notary public before entering the same chain.

Thailand acceded to the Hague Apostille Convention on 30 June 2026 and it enters into force for Thailand on 28 February 2027. After that date, documents from member states bearing an apostille no longer need Thai embassy legalisation, but still need a Thai translation.

Keep originals available for court, because the other party may ask to inspect them, and a court may decline a copy without good reason.

A Thai court may allow witness examination by videoconference under court rules, or send questions abroad through international channels, which is usually slow and depends on that country’s cooperation. Plan this from the start of the case.

A witness who does not speak Thai needs an interpreter accepted by the court, who must take an oath or affirmation before interpreting.

Under the Civil Procedure Code, documents in a foreign language generally need a certified Thai translation attached unless the court allows otherwise. The translation should cover every relevant part, including stamps, endorsements and certification text, as these can be important evidence.

Translators should use legal terms consistently and spell names of people, companies and places identically across all documents. If the other side disputes the translation, the court may order a new one or call the translator to testify, so choose a translator who is prepared to stand behind the work.

Emails, chat messages and digital files can be used as evidence under the Electronic Transactions Act and court rules. The key issue is showing the data has not been altered and came from the real sender, so keep original files with supporting data such as email headers and timestamps, rather than relying only on printouts or screenshots.

Where large volumes of data or authenticity disputes are involved, a digital forensics expert may need to examine the material and report. Plan for this early, as collecting evidence later can be harder.

A practical order is to identify the facts to be proved, select documents that address them directly, obtain certified copies from the issuing body, complete the certification steps of the home country and Thailand, translate into Thai with a certified translation, file the list of evidence with the court within the deadline, and line up a witness who can confirm the document’s origin if it is challenged.

Can a copy replace the original? Courts generally rely on originals but may accept copies in some cases, such as when the other side does not dispute them or the original is held by an agency. Always have the original or a copy certified by the issuer.

Can documents use an Apostille after 28 February 2027? Once the Convention is in force for Thailand, public documents from contracting states may use an Apostille instead of embassy legalisation, but they still need a Thai translation, and court practice should be checked at the time of filing.

What if documents are not ready before the hearing? A party may ask the court for more time or a postponement with reasons, at the court’s discretion, so start preparing foreign documents as early as possible.

Embassy legalisation or an Apostille only certifies the signature and capacity of the signer or the seal; it does not certify that the content is true. The court still weighs the evidence as usual, and the other side can still dispute the content. Another misunderstanding is that a machine translation can be filed in court, which is usually not enough, since a translator must certify accuracy and be ready to confirm it if challenged.

Also, documents obtained improperly, such as by accessing someone else’s email without permission, can create problems for admissibility and legal liability. Speak to a lawyer before gathering this kind of evidence.

Personal data protection is often overlooked. Foreign documents containing third-party data, such as health or financial details, should be used only as far as needed for the issues, and the court may be asked to protect or redact parts where appropriate. Transferring data across borders for litigation should take account of the Personal Data Protection Act and the law of the source country.

Where documents must be obtained from a foreign agency or person who will not provide them voluntarily, international judicial assistance may be needed, which involves several layers and takes time. Weigh how essential the document is and look for easier alternatives in parallel, such as copies the other party already holds or data from that country’s public registers.