ICDPASO Commercial Arbitration Rules Interpretation Series 29 “Evidence”

In modern international arbitration, fact-finding is advanced through four key stages: allocation of the burden of proof, submission and exchange of evidence, determinations on admissibility and evidentiary weight, and the taking and examination of witness/expert testimony. Article 29 of the International Commercial Dispute Prevention and Settlement Organization (ICDPASO) Commercial Arbitration Rules (the“Rules”) (the“Article 29”) adopts a four-paragraph structure to achieve these objectives.

Paragraph (1) establishes the foundational principle governing the allocation of the burden of proof (i.e., the starting point of proof obligations).

Paragraph (2) empowers the arbitral tribunal to issue procedural orders requiring the production of evidence (i.e., a mechanism for evidence production).

Paragraph (3) clarifies the tribunal’s authority to determine the admissibility, relevance, authenticity, and weight of evidence (i.e., the tribunal’s evaluative discretion).

Paragraph (4) sets out rules on witness and expert witness testimony: by treating written statements as the default, it reduces the cost of cross-border evidence-taking, while preserving fairness and flexibility by allowing the tribunal to determine the conditions and manner of any hearing/examination.

This structure preserves the procedural flexibility of arbitration while providing an enforceable framework for the tribunal’s discretion at key procedural junctures. It therefore helps reduce the risk of judicial review based on “procedural defects” and aligns clearly with the newly revised Arbitration Law of the People's Republic of China (the "New Arbitration Law") in areas such as proof, evidence collection, examination of evidence, and preservation of evidence.

I. Text of Article 29 of the Rules

Article 29. Evidence

1. The parties shall bear the burden of proof for the facts on which its claim or

defense is based.

2. The Arbitral Tribunal may, during the arbitral proceedings, require the parties to

present documents, physical objects or other evidence within the prescribed time limit.

3. The Arbitral Tribunal has the power to decide the admissibility, relevance, authenticity and weight of any evidence.

4. Unless otherwise directed by the Arbitral Tribunal, the statements of witnesses, including those of expert witnesses, may be submitted in writing after signed by such witnesses.

The hearing of witnesses, including expert witnesses, may be conducted in

accordance with the conditions and methods determined by the Arbitral Tribunal.

II. Clause-by-Clause Commentary on Article 29

Paragraph (1) Burden of Proof

1.Textual Analysis

This paragraph, in concise terms, establishes a basic proposition of arbitral procedure: a party bears the burden of proving the facts on which its claim or defence is based. The core is not the “standard of proof,” but rather the identification of thefacts underlying the claim or defence as the object of proof, thereby focusing the proceedings on disputed facts and facts constituting the legal elements of the claims and defences. The burden of proof is not borne solely by the claimant; instead, it follows the principle that “he who asserts must prove,” consistent in concept and logic with the New Arbitration Law, and reflects an institutional-rule level refinement of that principle.①

2. Comparative perspective

The UNCITRAL Model Law on International Commercial Arbitration (the “Model Law”) does not prescribe the allocation of the burden of proof article-by-article; rather, it leaves procedural matters largely to party autonomy and tribunal discretion (e.g., Article 19 empowers the tribunal to determine the admissibility and other attributes of evidence).② At the level of institutional rules, the ICC Arbitration Rules (2021) emphasize that the tribunal should establish the facts “as soon as possible by appropriate means” and may request additional evidence at any time, adopting a fact-finding approach rather than codifying burden-of-proof allocation in an express provision. Similar to the HKIAC Administered Arbitration Rules (2025), Article 29(1) instead states a clear default rule on the allocation of the burden of proof, reducing comprehension costs for parties from different jurisdictions.

3. Jurisprudential analysis

In essence, the burden of proof is a mechanism for allocating the risk of uncertainty where the truth or falsity of a fact remains unproven. If evidence is insufficient to establish a factual allegation, the party asserting that fact bears the adverse consequences. This function is particularly important in arbitration: compared with litigation, arbitration is relatively limited in access to state-backed investigative mechanisms. Without a clear rule on proof obligations as a procedural starting point, the tribunal may be drawn into an imbalanced confrontation characterized by delay tactics or “evidence ambush.” Further, burden-of-proof rules not only influence fact-finding but also support the procedural legitimacy and stability of an award in potential judicial review. If the tribunal clearly articulates—through procedural orders, hearing arrangements, and reasoning in the award—the allocation of proof obligations, the mapping between issues and proof responsibilities, and the required level of proof, it can help deter procedural challenges in set-aside or enforcement proceedings premised on allegations of inadequate opportunity to present one’s case or to prove one’s assertions.

4. Practical points

•Use procedural orders to create an “issues–burden–evidence” matrix, specifying for each issue the responsible party and the key evidence types (e.g., contract documents, performance records, expert reports).

•Properly arrange the presentation of evidence for defenses: Defenses (such as set-off, exemption from liability for breach, statute of limitations, etc.) often conceal counterfactuals. This provision has incorporated them into “facts relied upon in the defense.” Parties may consider avoiding treating defenses merely as legal opinions.

•Coordinate early with evidence preservation: where there is a risk of spoliation, promptly seek interim measures and/or evidence preservation mechanisms.

Paragraph (2) Order for Production of Evidence

1.Textual Analysis

This paragraph establishes a three-element framework—“may require,” “ within the prescribed time limit” and “documents, physical objects or other evidence”—authorizing the tribunal to require parties, on its own initiative as proceedings progress, to produce evidence, thereby transforming an abstract proof obligation into a tribunal-directed procedural order. “May require” indicates discretion rather than a mandatory duty; “within the prescribed time limit” imposes procedural discipline on evidence production; and “documents, physical objects or other evidence” covers diverse forms of evidence, including documentary evidence, physical evidence, audiovisual materials, electronic data, expert opinions, and inspection materials. The phrase “during the arbitral proceedings” indicates that this power applies throughout, including the written phase, pre-hearing, during the hearing, and post-hearing supplementation. The open-ended category “other evidence” leaves room for electronic records, site inspection materials, and third-party-generated materials, while the deadline is to be set by the tribunal.

2. Comparative perspective

The UNCITRAL Arbitration Rules (2021) provide that the tribunal may require parties to produce documents, exhibits, or other evidence within a specified period. ⑤The ICC Rules (2021) allow the tribunal to request additional evidence.⑥ The LCIA Arbitration Rules (2020) empower the tribunal to order the production for inspection of documents or goods within a party’s control.⑦ The SIAC Rules (2025) require written submissions to be accompanied by supporting documents and allow the tribunal to direct the simultaneous submission of witness statements and expert reports.⑧ Consistent with international practice, Article 29(2) converts evidence disclosure from a “negotiated arrangement” into a tribunal-order structure, well-suited to cases involving voluminous evidence and high cross-border evidence-taking costs.

3. Linkage with the New Arbitration Law

Article 55 of the New Arbitration Law affirms the parties’ burden to produce evidence, while also authorizing the tribunal, where necessary, to collect evidence on its own and to request assistance from relevant entities.⑨ Within this framework, Article 29(2) functions as a first-tier evidence-management mechanism: it prioritizes requiring parties to produce evidence by procedural order; where production is objectively impossible or refused, the tribunal can then assess whether to proceed under applicable law at the seat/place of administration to collect evidence or seek assistance, balancing cost, efficiency, and due process.

4. Practical points

In judicial review of arbitration, common grounds for challenge include whether evidence was examined and whether the opposing party had an opportunity to respond. Suggested practice includes:

•The arbitral tribunal's orders for the submission of evidence shall be issued in writing or recorded, clearly specifying the list, format, deadlines, and consequences of delay (such as exclusion or non-admission of evidence).

•A response period shall be provided following the issuance of such orders. Even in purely written proceedings, time shall be granted for cross-examination and rebuttal, and this shall be recorded in the procedural order or hearing minutes.

•For physical exhibits/samples, establish custody and sealing protocols to prevent contamination; for data evidence, add confidentiality and access controls.

Paragraph (3) Evaluation of Evidence

1.Textual Analysis

This paragraph clarifies that the tribunal’s evaluation of evidence proceeds along four dimensions:

Admissibility: Examining whether evidence meets the “entry requirements” for arbitration proceedings, i.e., whether a piece of evidence possesses evidentiary capacity and can be admitted as proof. For instance: Was the evidence lawfully obtained? Does the requested document fall under privilege? Can the witness accurately convey meaning? Was the evidence submitted within the evidentiary deadline?

Relevance: Determining whether evidence has a logical connection to the case's points at issue. Specifically, evidence must prove part or all of the facts to be established, typically through two forms of connection. Direct connection occurs when the facts reflected in the evidence constitute part or all of the facts to be proven. Indirect connection occurs when the facts reflected in the evidence indirectly support the establishment of a specific fact to be proven.

Authenticity: Evidence must represent objectively existing facts, particularly for contentious forms such as electronic data, photocopies, and unilaterally produced documents. Evidence materials should constitute authentic, objective records of the generation, development, and evolution of commercial legal relationships. Through these records, the arbitral tribunal adopts an objective stance to infer the establishment, changes, and true nature of legal relationships between parties and the substance of disputes.

Weight :This involves weighing the weight and value of evidence within the overall evidentiary framework. For instance, notarized documents and expert opinions carry relatively strong probative force and higher evidentiary weight.

2. Comparative perspective

The Model Law grants the tribunal discretion to determine the admissibility, relevance, materiality, and weight of evidence;⑩ the UNCITRAL Arbitration Rules (2021) adopt a similar approach.⑪ The SIAC Rules (2025) likewise empower the tribunal to decide admissibility, relevance, materiality, and weight without being bound by strict rules of evidence. The IBA Rules on the Taking of Evidence in International Arbitration (2020) similarly reflect these attributes, and LCIA, HKIAC and other institutional rules take a consistent position. Many international rules use the formulation of admissibility, relevance, materiality, and weight. Article 29(3), while retaining these internationally common elements, expressly lists authenticity, which aligns with PRC evidence law’s traditional focus on authenticity, legality, and relevance, and addresses courts’ concerns in set-aside review regarding whether key evidence was properly tested and whether the evidentiary basis is reliable.⑮

3. Jurisprudential analysis

Evidence assessment in arbitration is not about mechanically applying a fixed evidentiary code; rather, it is about giving the tribunal reasonable and flexible discretion. The role of Article 29(3) is to make the basis and boundaries of that discretion clearer. When the tribunal conducts a structured analysis around “admissibility–relevance–authenticity– weight ,” fact-finding becomes an intelligible line of reasoning that parties can understand and scrutinize. This enhances perceived procedural fairness and strengthens the persuasiveness and stability of the award at the recognition and enforcement stage.

4. Practical points

•In procedural orders or minutes of an evidentiary conference, specify in advance the form of evidence submission, confidentiality tiers, and how late evidence will be handled, creating a procedural benchmark for later review.

•Where a party challenges admissibility or authenticity of key evidence, issue timely rulings and record the reasons to avoid deferring disputes to the award stage.

•In the award, consider a dedicated section on evidentiary assessment using an “issue–evidence–reasons–conclusion” structure.

For specific types of evidence:

•Expert opinions: if the materials relied upon for an expert conclusion were not examined/challenged, it may be viewed as a procedural violation. The tribunal should ensure the underlying materials are subject to challenge and that the expert can be questioned—consistent with Article 56 of the New Arbitration Law.⑯

•Late-submitted evidence, especially electronic data: clarify whether it is admitted, the scope of admission, and the opposing party’s opportunity to rebut, and, where appropriate, explain the tribunal’s reasoning by reference to admissibility, authenticity, relevance, and weight to minimize challenge risk.

Paragraph (4) Witness / Expert Witness Testimony

1.Textual Analysis

The first sentence of this provision establishes that witness statements (including expert witness) may be submitted in writing unless otherwise directed by the arbitral tribunal, provided they are signed by the witness personally. The second sentence authorizes the arbitral tribunal to conduct hearings of witnesses/experts under conditions and in a manner determined by the tribunal. This institutional design carries three implications.

Written testimony as the default format helps reduce arbitration costs associated with witness attendance and facilitates pre-trial clarification of testimony scope and content;

The requirement for “personal signature” assigns responsibility for the testimony and its authenticity to the individual witness, enhancing credibility and facilitating the resolution of disputes arising from the authenticity of the testimony.

The manner of examination may be flexibly arranged (e.g., in person, remotely, or a hybrid format; written testimony followed by cross-examination; or in-person confrontation of experts), balancing procedural efficiency with the parties' right to cross-examination.

2. Comparative perspective

The LCIA Rules (2021) provide that witness evidence may be given by signed written statement and allow the tribunal to control the procedure for questioning witnesses; similar provisions apply to expert witnesses.⑰ The SIAC Rules (2025) authorize the tribunal to require witness statements and expert reports and regulate the appearance of witnesses and the scope of oral testimony, reflecting careful governance of how testimony is formed.⑱ The ICC Rules (2021) allow the tribunal to hear witnesses and experts and, upon party request, arrange the examination of experts.⑲ Article 29(4) is therefore consistent with international institutional practice and is particularly suitable for complex cross-border cases involving dispersed witnesses, multiple languages, and high travel costs.

3. Practical points

•Standardize written witness statements: include a signature page, identity information, and a statement of truth; where appropriate in cross-border cases, consider notarization, legalization, or witnessed execution to enhance credibility.

•Carefully design the examination procedure: specify whether the hearing will be in-person/remote/hybrid; whether to use concurrent expert evidence; whether cross-examination will be permitted and time limits—ideally all set out in a procedural order.

•Confidentiality and data compliance: where statements involve confidential information, the tribunal may impose access controls (e.g., “attorneys’ eyes only”) and record the reasons to reduce procedural challenge risk.

III. Linkage with the New PRC Arbitration Law

From the perspective of the procedural chain, Article 55 of the New Arbitration Law confirms the partie’ burden of proof and empowers the tribunal, where necessary, to collect evidence and request assistance;⑳Article 58 establishes evidence preservation and court assistance mechanisms.㉑ Article 29 of the Rules creates an institutional operational framework—“party production → tribunal order for production → tribunal evaluation of evidence”—which aligns with the New Arbitration Law’s direction of strengthening tribunal evidence-taking capacity and judicial support, and is particularly valuable in cross-border cases where evidence is located in multiple jurisdictions.

On the management of the right to examine/challenge evidence, Article 57 of the New Arbitration Law emphasizes that evidence should be presented and examined at a hearing and that parties have the right to challenge evidence.㉒Article 29(4) responds to international arbitral practice by allowing written testimony while entrusting the tribunal to manage the concrete arrangements for examination, thereby safeguarding the opportunity to challenge evidence while enabling effective procedural management.

IV. Conclusion

Through its four-paragraph structure, Article 29 establishes a procedural governance framework for evidence in ICDPASO commercial arbitration that combines flexibility with predictability. It begins with the allocation of the burden of proof, clarifying the boundaries of the principle that “he who asserts must prove”; it then grants the tribunal an evidence-production ordering power throughout the proceedings, transforming abstract proof obligations into enforceable procedural discipline; at its core, it vests the tribunal with a complete evaluative authority over admissibility, relevance, authenticity, and weight, enabling case-sensitive discretion; and finally, it reduces cross-border evidence-taking costs by treating written witness statements as the default while preserving parties’ rights to challenge evidence through flexible tribunal-managed examination arrangements.

This design equips tribunals with tools to ascertain facts efficiently and control procedural tempo, while safeguarding parties’ reasonable opportunities to present and challenge evidence. By aligning with the New Arbitration Law on proof, evidence collection, and examination, it also strengthens an award’s resilience against “procedural defect” challenges in subsequent set-aside and enforcement proceedings.

①Arbitration Law of the People's Republic of China (2025 Revision) art.55, which provides that: “A party shall provide evidence in support of its own claims.

The arbitration tribunal may, as it considers necessary,collect evidence on its own initiative, and may, when necessary, request relevant entities to provide assistance in accordance with the law.”

②UNCITRAL Model Law on International Commercial Arbitration (1985), with amendments as adopted in 2006 art Article 19. Determination of rules of procedure which provides that: “ (1) 

Subject to the provisions of this Law, the parties are free to agree on the procedure to be followed by the arbitral tribunal in conducting the proceedings.

(2)Failing such agreement, the arbitral tribunal may, subject to the provisions of this Law, conduct the arbitration in such manner as it considers appropriate. The power conferred upon the arbitral tribunal includes the power to determine the admissibility, relevance, materiality and weight of any evidence.”

③ICC 2021 Arbitration Rules art. 25 Establishing the Facts of the Case, which provided that: “1)

The arbitral tribunal shall proceed within as short a time as possible to establish the facts of the case by all appropriate means.

.............

4)

At any time during the proceedings, the arbitral tribunal may summon any party to provide additional evidence.”

④HKIAC 2024 Administered Arbitration Rules art 22.1, which provided that: “Each party shall have the burden of proving the facts relied on to support its claim or defence.”

⑤UNCITRAL Arbitration Rules(2021)art 27.3 , which provided that: “At any time during the arbitral proceedings the arbitral tribunal may require the parties to produce documents, exhibits or other evidence within such a period of time as the arbitral tribunal shall determine.”

⑥ICC 2021 Arbitration Rules art. 25.4 , which provided that:“At any time during the proceedings, the arbitral tribunal may summon any party to provide additional evidence.”

⑦LCIA Rules（2020）art.22.1.(i), which provides that: “The Arbitral Tribunal shall have the power, upon the application of any party or (save for sub- paragraph (x) below) upon its own initiative, but in either case only after giving the parties a reasonable opportunity to state their views and upon such terms (as to costs and otherwise) as the Arbitral Tribunal may decide:

(iv) to order any party to make any documents, goods, samples, property, site or thing under its control available for inspection by the Arbitral Tribunal, any other party, any expert to such party and any expert to the Tribunal;...

⑧SIAC Rules（2025）art.33.7,which provides that: “All submissions referred to in this Rule 33 shall be accompanied by copies of all supporting documents which have not previously been submitted by any party. The Tribunal may direct, after considering the views of the parties, that written submissions shall be accompanied by copies of supporting witness statements and expert reports.”

⑨Arbitration Law of the People's Republic of China (2025 Revision) art.55, which provides that: “A party shall provide evidence in support of its own claims.

The arbitration tribunal may, as it considers necessary,collect evidence on its own initiative, and may, when necessary, request relevant entities to provide assistance in accordance with the law.”

⑩UNCITRAL Model Law on International Commercial Arbitration (1985), with amendments as adopted in 2006 art Article 19.(2), which provides that: “Failing such agreement, the arbitral tribunal may, subject to the provisions of this Law, conduct the arbitration in such manner as it considers appropriate. The power conferred upon the arbitral tribunal includes the power to determine the admissibility, relevance, materiality and weight of any evidence.”

⑪UNCITRAL Arbitration Rules(2021) art 27.4 , which provided that: “The arbitral tribunal shall determine the admissibility, relevance, materiality and weight of the evidence offered.”

⑫SIAC Rules（2025）art.32.3, which provides that: “The Tribunal shall determine the admissibility, relevance, materiality, and weight of all evidence. The Tribunal is not required to apply the rules of evidence of any applicable law in making such a determination.”

⑬IBA (International Bar Association) Rules on the Taking of Evidence in International Arbitration (2020) art.9.1, which provides that: “The Arbitral Tribunal shall determine the admissibility, relevance, materiality and weight of evidence.”

⑭LCIA Rules（2020）art.22.1, which provides that: “(vi) to decide whether or not to apply any strict rules of evidence (or any other rules) as to the admissibility, relevance or weight of any material tendered by a party on any issue of fact or expert opinion; and to decide the time, manner and form in which such material should be exchanged between the parties and presented to the Arbitral Tribunal;”

HKIAC 2024 Administered Arbitration Rules art 22.2, which provided that: “The arbitral tribunal shall determine the admissibility, relevance, materiality and weight of the evidence, including whether to apply strict rules of evidence.”

⑮Article 104 of the Interpretation of the Supreme People's Court on the Application of the Civil Procedure Law of the People's Republic of China, which provides that: “The people's court shall organize the parties to cross-examine the authenticity, legality, and relevance of evidence to the facts to be proven, and shall explain and debate whether the evidence has probative value and the extent of such value.

Evidence that reflects the true circumstances of the case, is relevant to the facts to be proven, and complies with legal requirements regarding its source and form shall be used as the basis for determining the facts of the case."

⑯Arbitration Law of the People's Republic of China (2025 Revision) art.56, which provides that: “A party may apply to the arbitration tribunal for an expert opinion on a specialized issue concerning ascertainment of facts. An arbitration tribunal may, on application or as it deems necessary, refer the issue requiring an expert opinion to an expert witness agreed on by the parties or designated by it.

At the request of the parties or as required by the arbitration tribunal, the expert witness shall attend the hearing upon notification by the arbitration tribunal. Subject to the permission of the arbitration tribunal, theparties may question the appraiser.”

⑰LCIA Rules（2020）art.20,which provides that: “20.3 Subjectto any order otherwise by the Arbitral Tribunal, the testimony of a witness may be presented by a party in written form, either as a signed statement or like document.

20.5 The Arbitral Tribunal and any party may request that a witness, on whose written testimony another party relies, should attend for oral questioning at a hearing before the Arbitral Tribunal. If the Arbitral Tribunal orders that other party to secure the attendance of that witness and the witness refuses or fails to attend the hearing without good cause, the Arbitral Tribunal may place such weight on the written testimony or exclude all or any part thereof altogether as it considers appropriate in the circumstances.

20.8 Subject to the mandatory provisions of any applicable law, the Arbitral Tribunal shall be entitled (but not required) to administer any appropriate oath or affirmation to any witness at any hearing, prior to the oral testimony of that witness.

20.9 Any witness who gives oral testimony at a hearing before the Arbitral Tribunal may be questioned by each of the parties under the control of the Arbitral Tribunal. The Arbitral Tribunal may put questions at any stage of such testimony.”

LCIA Rules（2020）art.21,which provides that: “21.1 The Arbitral Tribunal, after consultation with the parties, may appoint one or more experts to report in writing to the Arbitral Tribunal and the parties on specific issues in the arbitration, as identified by the Arbitral Tribunal.

21.4 If any party so requests or the Arbitral Tribunal considers it necessary, the Arbitral Tribunal may order the expert, after delivery of the expert’s written report, to attend a hearing at which the parties shall have a reasonable opportunity to question the expert on the report and to present witnesses in order to testify on relevant issues arising from the report. Articles 20.8 and 20.9 of the LCIA Rules shall apply, with necessary changes, to any expert to the Arbitral Tribunal.

⑱SIAC Rules（2025）art.40 which provides that: “40.1 Prior to any hearing, the Tribunal may direct the parties to give notice of the identity of witnesses, including expert witnesses, whom the parties intend to produce, the subject matter of their testimony, and its relevance to the issues.

40.2 The Tribunal shall have the power to order or refuse to allow the appearance of witnesses to give oral evidence at any hearing or to limit oral witness testimony at any hearing.

40.4 The Tribunal may direct the testimony of witnesses to be presented in written form, either as signed or sworn statements or any other form of recording. Subject to Rule 40.2, any party may request that such a witness attend a hearing for oral examination, whether in-person, by videoconference, teleconference, or any other form of electronic communication. If the witness fails to attend for oral examination, the Tribunal may determine the weight to be placed on such written testimony, disregard such written testimony, or exclude such written testimony altogether.”

⑲ICC 2021 Arbitration Rules art. 25 Establishing the Facts of the Case, which provided that: “2) The arbitral tribunal may decide to hear witnesses, experts appointed by the parties or any other person, in the presence of the parties, or in their absence provided they have been duly  summoned.

3)The arbitral tribunal, after consulting the parties, may appoint one or more experts, define their terms of reference and receive their reports. At the request of a party, the parties shall be given the opportunity to question at a hearing any such expert.

⑳Arbitration Law of the People's Republic of China (2025 Revision) art.55, which provides that: “A party shall provide evidence in support of its own claims.

The arbitration tribunal may, as it considers necessary,collect evidence on its own initiative, and may, when necessary, request relevant entities to provide assistance in accordance with the law.”

㉑Arbitration Law of the People's Republic of China (2025 Revision) art.58, which provides that: “Where any evidence may be destroyed or lost or difficult to obtain at a later time, a party may apply for evidence preservation. If a party applies for evidence preservation, the arbitral institution shall refer the application to the primary people's court at the place where the evidence is located, and the people's court shall handle it in a timely manner in accordance with the law.

In case of emergency, a party to an arbitration agreement may, before applying for arbitration, apply to the people's court for evidence preservation in accordance with the relevant provisions of the Civil Procedure Law of the People's Republic of China. If a party applies for evidence preservation, the people's court shall handle it in a timely manner in accordance with the law.”

㉒Arbitration Law of the People's Republic of China (2025 Revision) art.57, which provides that: “Evidence shall be presented during a hearing,and may be examined by the parties.”