Affidavit of Foreign Law

Affidavit of Foreign Law. When a Thai court, administrative body or arbitral tribunal must apply the law of another jurisdiction, the standard way to prove that foreign law is by a sworn affidavit of foreign law (an expert, notarized statement describing what the foreign law is and how it applies). Done correctly it short-circuits uncertainty and speeds resolution; done badly it creates adjournments, extra expert rounds and costs. This is a practical playbook you can use immediately: who to instruct, how to structure the affidavit, authentication and translation steps, tactical uses, timings/costs and an execution checklist.

Why courts want an affidavit of foreign law

Thai judges are not expected to know the laws of other jurisdictions. The affidavit performs three narrow, but vital functions:

1. State the content of the foreign law (statutes, regulations, leading cases).

2. Explain how foreign courts apply those rules in practice (interpretive lines, exceptions, remedies).

3. Apply those legal rules to the assumed facts the tribunal is being asked to accept.

It is evidence about law, not fact. If the other party disputes the affidavit the court allows a rebuttal affidavit or orders expert questioning.

Who to appoint — pick credibility and availability

Choose an author the court can test:

• A practicing lawyer admitted in the foreign jurisdiction (best where up-to-date case law and practice matter).

• A senior academic with peer-reviewed work (useful for doctrinal, comparative or historical questions).

The affiant should give a short CV (admission year, firm/university, notable cases/publications), explain research methods and state they are available for cross-examination (video attendance is normally acceptable). Judges prefer authors whose credentials they can readily verify.

Recommended structure — concise, numbered, scannable

Use a modular, numbered format so judges and clerks can find answers quickly:

1. Caption & instruction statement — case caption; who instructed the expert and the precise legal questions posed.

2. Qualifications — short CV and basis of expertise.

3. Assumed facts (Annex A) — numbered facts the expert is asked to assume (the expert must assume facts; do not ask them to decide contested factual issues).

4. Legal propositions — short, numbered statements of the foreign law (each with pinpoint citations to statutes or cases). Keep propositions discrete and citable.

5. Application — reasoned application of each proposition to the assumed facts with paragraph cross-references.

6. Sources & method — the databases/resources searched and the date the research was current to.

7. Exhibits — full texts of statutes and full judgments relied on (not extracts), each paginated and labelled.

8. Caveats — identify significant contrary authorities and explain weight.

9. Oath / notarial block — sworn before a competent officer.

Number every paragraph and exhibit; include a short table mapping propositions to supporting exhibits.

Authentication & legalization — do it early

Authentication is the frequent cause of adjournments. The correct sequence for foreign affidavits used in Thailand is:

1. Swear the affidavit in the foreign jurisdiction before an authorized officer (notary public or equivalent).

2. Apostille the notary signature if the country is a Hague Convention member. If not, obtain consular legalization (foreign ministry authentication + Thai consulate legalization). This step proves the notary’s authority.

3. Certified Thai translations of the affidavit and every attached authority. The translator should sign a translator’s declaration attesting accuracy. Some Thai tribunals require legalization of the translator’s signature — check local practice.

4. File originals or certified copies as required by the court, tribunal or administrative body and retain apostilled originals for inspection.

Start legalization and translation weeks before the hearing — apostille and consular slots can be slow.

Exhibits — attach full primary materials

Attach the entire statute texts and whole judicial opinions, not cherry-picked snippets. For unreported decisions include the full judgment. Where law varies regionally (states, provinces), identify the territorial scope. Judges value completeness: provide the materials they need to test the expert’s reasoning.

Tactical uses and timing

• File early when foreign law is dispositive (recognition of foreign judgments, foreign insolvency, validity of foreign marriages). Early filing avoids wasted hearings.

• Budget for rebuttal: the opponent will often file a rebuttal affidavit; plan for one.

• Propose a joint expert or ask the tribunal to appoint a neutral expert where both sides agree — this is faster and cheaper in many cases.

• Ensure the expert’s availability for the hearing (video links are usually allowed). Courts expect the author to be reachable for questioning if law is contested.

If foreign law is central, lock down the expert and begin legalization at least 3–4 weeks before the hearing.

Practical drafting tips judges appreciate

• Use short numbered legal propositions rather than long essays.

• State the research cut-off date (e.g., “research current to 1 June 2025”).

• Where law is unsettled, identify the competing lines and explain which you prefer and why. Judges value candor.

• Keep factual assumptions in an annex and cross-reference them clearly.

• Ask the expert to preserve working notes and search logs (the court may inspect them if the other side asks).

Timelines & realistic costs

• Research & drafting: 1–3 weeks for common jurisdictions; longer for obscure or complex comparative work.

• Notarization + apostille/consular legalization: 3–14 business days depending on country and consulate workload.

• Translation: 2–7 business days depending on volume.

• Costs: from a few hundred USD for a simple affidavit to several thousand USD for senior experts, extensive research, rush work, translations and legalization. Always budget for a rebuttal affidavit and possible expert attendance at the hearing.

Common pitfalls & how to avoid them

• Opinion letters instead of sworn affidavits — weaker and sometimes inadmissible. Use a sworn, legalized affidavit.

• Poor translations that alter legal meaning — use certified legal translators experienced in the source system.

• Blurring law and fact — do not ask the expert to decide contested factual issues; they must assume facts in Annex A.

• Unavailable expert — secure a written availability undertaking for hearings (video attendance).

Run a pre-execution checklist to prevent these mistakes (see below).

Model short clause (ready to adapt)

“I, [Name], admitted as an advocate and solicitor in [Jurisdiction] in [Year], of [Firm], being duly sworn, say: I have been instructed by [Party] to advise on the law of [Jurisdiction] on the following questions: (1) [Question 1]; (2) [Question 2]. The facts set out in Annex A are assumed. My opinion is based on the documents listed in Annex B. Attached as Exhibits 1–N are the primary authorities relied upon. To the best of my knowledge and after the inquiries I describe, the matters contained in this affidavit are true.”

Pre-execution checklist (what to do now)

1. Agree the precise legal questions with counsel.

2. Prepare an Annex A of agreed facts or ask the court to fix assumed facts.

3. Instruct a credentialed foreign lawyer/academic and confirm availability for hearing.

4. Fix a research cut-off date and ask for a search statement.

5. Arrange notarization and apostille/consular legalization early.

6. Order certified Thai translations of affidavit and exhibits.

7. File per tribunal rules and retain originals and apostilles.

Final practical note

An affidavit of foreign law is a specialist, evidence-driven deliverable: treat it like an expert report. Pick a credible author, define precise legal questions, attach full primary authorities, authenticate and translate everything properly, and budget for rebuttal and oral testimony.