Evidence, Witnesses and Expert Reports in Turkish Arbitration

Evidence is often the decisive element in Turkish arbitration proceedings. A party may have a commercially justified claim, but it will not succeed merely by alleging that the other party breached the contract. The claimant must establish the facts supporting its claim, while the respondent must prove the factual basis of its defences, set-off allegations and counterclaims.

International and domestic arbitrations seated in Türkiye provide the parties and arbitral tribunal with substantial flexibility concerning the presentation and evaluation of evidence. The proceedings do not necessarily follow every formal rule applied in ordinary Turkish court litigation.

Depending on the arbitration agreement, applicable institutional rules and procedural orders, evidence may include:

• Commercial contracts and amendments;
• Emails and messaging records;
• Accounting documents;
• Project reports;
• Technical data;
• Electronic records;
• Witness statements;
• Oral witness testimony;
• Party-appointed expert reports;
• Tribunal-appointed expert reports;
• Physical inspections;
• Samples, machinery and digital systems.

The principal legislation governing foreign-element arbitrations seated in Türkiye is International Arbitration Law No. 4686. Domestic arbitrations are governed by Articles 407 to 444 of the Turkish Code of Civil Procedure No. 6100.

Turkish arbitration law recognises party autonomy while protecting equal treatment and the right to present a case. Under Article 8 of Law No. 4686, the parties may agree on the procedural rules directly or by referring to national, international or institutional arbitration rules. In the absence of an agreement, the tribunal conducts the proceedings under the statutory framework. The parties must be given equal procedural rights and an opportunity to present their claims and defences.

This article explains the legal framework governing evidence, documentary production, witness testimony, cross-examination, expert reports, physical inspections, electronic records and judicial assistance in Turkish arbitration proceedings.

The Legal Framework for Evidence in Turkish Arbitration

The applicable evidentiary procedure depends on several sources.

These may include:

1. The arbitration agreement;
2. The law of the arbitral seat;
3. The institutional or ad hoc arbitration rules;
4. Procedural orders issued by the tribunal;
5. Any evidentiary rules adopted by the parties or tribunal;
6. Mandatory requirements protecting equality and the right to be heard.

International Arbitration Law No. 4686 does not establish an exhaustive evidence code comparable to the detailed provisions governing ordinary court litigation. Instead, it grants the parties broad freedom to design the procedure and allows the tribunal to conduct the arbitration within the limits of mandatory law.

Article 10 permits the parties to submit written evidence with their pleadings and identify evidence that they intend to produce later. Articles 11 and 12 regulate hearings, disclosure of submissions to the opposing party, expert appointments, inspections and court assistance in collecting evidence.

Domestic arbitration follows a similar approach. Articles 423 and 424 of the Turkish Code of Civil Procedure protect equality and the right to be heard while allowing the parties to select the applicable procedure. Articles 429 to 432 regulate hearings, expert evidence and judicial assistance.

The result is a flexible evidentiary system. The tribunal is not required to admit every document or hear every witness proposed by a party. It may determine which evidence is relevant, material, proportionate and necessary for resolving the dispute.

Evidence Should Be Addressed at the First Procedural Conference

The evidentiary process should be planned at an early stage.

After the tribunal is constituted, the parties and tribunal will ordinarily discuss procedural matters during a case-management conference. The resulting procedural order may address:

• The sequence of written submissions;
• Deadlines for submitting documents;
• Witness statement requirements;
• Expert report requirements;
• Document production;
• Confidentiality;
• Electronic document formats;
• Translation;
• Physical inspections;
• The structure of the evidentiary hearing;
• Remote testimony;
• Hearing bundles;
• Transcripts.

Early agreement reduces the risk of later disputes and ensures that both parties understand how evidence will be presented.

The 2020 IBA Rules on the Taking of Evidence in International Arbitration encourage the tribunal to consult the parties at the earliest appropriate stage concerning witness statements, expert reports, oral testimony, document production, confidentiality, cybersecurity, data protection and procedural efficiency. The IBA Rules are not automatically binding in every Turkish arbitration, but the parties or tribunal may adopt them in full, in part or as procedural guidelines.

Burden of Proof

The general starting point is that each party must prove the facts on which it relies.

The claimant should prove:

• The existence of the contractual or legal obligation;
• The respondent’s breach;
• Causation;
• The existence and amount of loss;
• Compliance with contractual notice requirements;
• Any other facts necessary for the requested remedy.

The respondent should prove:

• Payment;
• Performance;
• Release;
• Set-off;
• Limitation;
• Force majeure;
• Contributory conduct;
• Mitigation failures;
• Facts supporting its counterclaims.

The precise burden may also depend on the substantive law governing the dispute.

For example, the applicable substantive law may allocate the burden regarding product defects, payment, negligence, contractual notices, limitation periods or exemptions from liability.

The tribunal should distinguish between the burden of producing evidence and the ultimate burden of persuasion. A party may initially establish a fact through credible evidence, after which the opposing party may need to produce evidence capable of rebutting it.

Standard of Proof

Turkish arbitration legislation does not establish one universal evidentiary standard for every type of claim.

In ordinary commercial disputes, tribunals commonly decide facts on the basis of the evidence they consider more persuasive and probable.

Certain allegations may require particularly convincing evidence because of their seriousness. These may include:

• Fraud;
• Corruption;
• Forgery;
• Bad faith;
• Deliberate concealment;
• Sham transactions.

The tribunal should identify the evidentiary standard it applies consistently and avoid imposing an unfair or unexpected standard after the evidentiary record has closed.

A party making a serious allegation should support it with documents, credible witness evidence, expert analysis and a coherent factual chronology rather than relying on suspicion or general accusations.

Documentary Evidence

Documents are usually the foundation of commercial arbitration.

Relevant documents may include:

• Signed contracts;
• Amendments;
• Purchase orders;
• Invoices;
• Payment records;
• Bank statements;
• Board minutes;
• Technical specifications;
• Progress reports;
• Notices;
• Correspondence;
• Photographs;
• Audio or video files;
• Accounting records;
• Regulatory documents;
• Computer data.

International Arbitration Law permits parties to attach written evidence to their submissions and identify evidence to be submitted later. The tribunal establishes the timetable and may refuse late evidence where its submission would cause unfairness, disruption or unnecessary delay.

A party should not submit every document in its possession without organisation. The evidence should be connected to specific allegations through:

• Exhibit numbers;
• Chronologies;
• References in written submissions;
• Document indexes;
• Witness statements;
• Expert reports.

A large quantity of irrelevant material may obscure the strongest evidence and increase the duration and cost of the proceedings.

Document Production

Document production allows a party to request relevant documents held by the opposing party.

Unlike broad discovery in some court systems, international arbitration document production is generally intended to remain focused and proportionate.

A party should ordinarily identify:

• The specific document or narrow category requested;
• Why it is believed to exist;
• Why it is relevant;
• Why it is material to the outcome;
• Why it is believed to be within the other party’s possession, custody or control.

Under the IBA Rules, document requests should identify either a specific document or a narrow and specific category reasonably believed to exist. For electronic records, the requesting party may be required to identify files, custodians, search terms or other efficient search methods.

Overly broad requests such as “all correspondence concerning the project” may be rejected for lack of specificity, excessive burden or insufficient materiality.

A well-drafted request might instead seek:

“Emails exchanged between the project manager and the procurement director between 1 March and 30 April 2025 concerning the cancellation of Purchase Order No. 1187.”

This wording identifies the custodians, timeframe, subject matter and document category.

Redfern Schedules

Document production requests are frequently organised through a Redfern Schedule.

A Redfern Schedule typically contains separate columns for:

• The document requested;
• Relevance and materiality;
• The responding party’s objection;
• The requesting party’s reply;
• The tribunal’s decision.

The schedule helps the tribunal resolve document disputes efficiently without lengthy separate submissions.

The use of a Redfern Schedule is not compulsory under Turkish legislation. It is a procedural tool that may be adopted through party agreement or a tribunal order.

Objections to Document Production

A party may object to a document request on grounds such as:

• Lack of relevance;
• Lack of materiality;
• Excessive breadth;
• Unreasonable burden;
• Legal privilege;
• Confidentiality;
• Data protection;
• Loss or destruction;
• Lack of possession, custody or control;
• Illegality in obtaining the evidence;
• Procedural unfairness.

The IBA Rules authorise tribunals to exclude evidence because of legal impediment or privilege, unreasonable burden, compelling commercial confidentiality, political sensitivity, proportionality, fairness or equality. They also permit tribunals to exclude illegally obtained evidence.

The party objecting should explain the factual and legal basis rather than making a general claim that documents are “confidential.”

Confidentiality may justify protection, redaction, limited access or a confidentiality order rather than complete non-production.

Legal Privilege

Privilege questions may become difficult where parties and counsel come from different legal traditions.

One jurisdiction may protect communications with in-house counsel, while another may recognise protection only for independent lawyers. The parties may also have different rules governing settlement communications, internal investigations and legal advice.

The tribunal should determine:

• Which privilege rules apply;
• The expectations of the parties when the communication was created;
• Whether privilege was waived;
• Whether fairness requires a uniform approach;
• Whether part of the document can be redacted.

The IBA Rules permit tribunals to consider the need to protect communications made for obtaining legal advice or conducting settlement negotiations, the parties’ expectations, possible waiver and the need to maintain equality between parties subject to different legal or ethical rules.

Privilege issues should be raised promptly. Voluntary disclosure of a privileged document may result in waiver depending on the applicable legal and procedural framework.

Confidentiality and Commercially Sensitive Documents

Commercial arbitrations may involve:

• Trade secrets;
• Pricing formulas;
• Customer lists;
• Source code;
• Technical designs;
• Personal data;
• Bank records;
• Regulatory information.

The tribunal may protect sensitive evidence through:

• Redaction;
• Confidentiality undertakings;
• Restricted-access data rooms;
• Counsel-only disclosure;
• Expert-only disclosure;
• Sealed hearing sessions;
• Restrictions on copying or use.

Under the IBA Rules, non-public documents produced in the arbitration are generally to be used only for the proceedings, subject to exceptions where disclosure is legally required or necessary for enforcing or challenging the award. Tribunals may issue detailed confidentiality orders.

The party requesting protection should identify the specific risk rather than claiming that the entire evidentiary record is commercially sensitive.

Electronic Evidence and Metadata

Modern arbitration increasingly depends on electronic records.

Relevant electronic evidence may include:

• Emails;
• Messaging applications;
• Enterprise-resource-planning records;
• Server logs;
• Cloud files;
• Digital photographs;
• GPS data;
• Building information models;
• Electronic signatures;
• Spreadsheet formulas;
• Database records;
• Mobile-device data.

A printout may not reveal:

• The original author;
• Creation date;
• Modification history;
• Deleted content;
• Email attachments;
• Hidden spreadsheet formulas;
• Metadata;
• Whether the file was altered.

Where authenticity is disputed, the tribunal may require production in native electronic format or request technical expert analysis.

The IBA Rules recognise documents as information recorded on paper, electronically, visually, through audio or by other means. They also permit targeted electronic searches using specified files, individuals or search terms.

Parties should preserve electronic evidence as soon as a dispute becomes reasonably foreseeable. Automatic deletion, device replacement or uncontrolled alteration may destroy material evidence and expose the party to adverse inferences.

Authenticity of Documents

Submitting a document does not necessarily establish that it is authentic.

Authenticity disputes may concern:

• Signatures;
• Altered dates;
• Edited emails;
• Manipulated screenshots;
• Incomplete message chains;
• Fabricated invoices;
• Modified spreadsheets;
• Unreliable translations.

The challenging party should identify the basis of its objection. A general denial may be insufficient where the document is supported by metadata, related correspondence or commercial conduct.

The tribunal may consider:

• The original document;
• Metadata;
• Witness evidence;
• Expert examination;
• Consistency with other records;
• Whether the document was used contemporaneously;
• Whether the opposing party previously accepted it.

The tribunal may order inspection of the original where a copy’s conformity is disputed. Under the IBA Rules, copies should correspond to the originals, and the tribunal may request presentation of an original for inspection.

Witnesses of Fact

A witness of fact gives evidence about events personally observed or known.

Witnesses may include:

• Employees;
• Former employees;
• Directors;
• Project managers;
• Accountants;
• Engineers;
• Customers;
• Suppliers;
• Consultants;
• Government representatives;
• Other persons with first-hand knowledge.

International arbitration practice does not automatically disqualify a witness because that person is connected with a party.

Under the IBA Rules, any person may provide evidence, including a party, officer, employee or representative. The relationship affects the weight and credibility of the testimony rather than its automatic admissibility.

The tribunal will assess:

• The witness’s opportunity to observe the events;
• Internal consistency;
• Consistency with contemporaneous documents;
• Commercial interest;
• Memory;
• Demeanour;
• Responses during questioning.

A senior executive with an obvious interest in the outcome may still provide important evidence, particularly where the testimony is supported by contemporaneous records.

Written Witness Statements

Witness evidence is frequently submitted initially in writing.

A witness statement should ordinarily contain:

• The witness’s identity;
• Position and relationship with the parties;
• Relevant professional background;
• A chronological description of facts;
• The source of the witness’s knowledge;
• References to supporting documents;
• Confirmation of truth;
• Signature, date and place.

Under the IBA Rules, witness statements should describe the facts and source of information in sufficient detail to serve as the witness’s direct testimony. Documents relied upon but not already submitted should be attached or produced with the statement.

A witness should explain facts personally known rather than present lengthy legal argument.

Statements that appear to have been written entirely by counsel, use identical language across several witnesses or contain matters outside the witness’s knowledge may receive reduced weight.

Witness Preparation

Counsel may meet with witnesses to:

• Understand their knowledge;
• Review documents;
• Explain the procedure;
• Prepare a truthful witness statement;
• Familiarise the witness with cross-examination;
• Identify language or interpretation needs.

Under the IBA Rules, it is not improper for a party, counsel or representative to interview witnesses and discuss their prospective testimony.

Preparation must not become coaching.

Counsel should not:

• Invent facts;
• Ask the witness to adopt words that are untrue;
• Conceal material weaknesses;
• Rehearse a false answer;
• Encourage speculation;
• Coordinate witnesses to give artificially identical accounts.

The witness should understand that credibility depends on giving honest answers, including saying that they do not remember or do not know.

Oral Testimony and Cross-Examination

At the evidentiary hearing, witnesses may be questioned about their written statements and the documentary record.

The usual sequence may include:

1. Confirmation of identity and witness statement;
2. Limited direct examination;
3. Cross-examination by the opposing party;
4. Re-examination on issues raised during cross-examination;
5. Questions from the tribunal.

The tribunal controls the hearing and may limit questions that are irrelevant, repetitive, disproportionate or unfair.

Under the IBA Rules, the tribunal has complete control over the evidentiary hearing, may limit questions and may ask questions at any time. The Rules also recognise cross-examination, re-examination and the possibility that written statements will stand as direct testimony.

Cross-examination should test credibility and accuracy rather than merely intimidate the witness.

Effective questions may focus on:

• Contradictions;
• Contemporaneous documents;
• Gaps in memory;
• Commercial interests;
• Inconsistent accounts;
• Events outside the witness’s personal knowledge.

Failure of a Witness to Appear

Where the opposing party requests the attendance of a witness who submitted a statement, failure to appear may affect the evidential value of that statement.

Under the IBA Rules, a tribunal may disregard a witness statement if the witness fails to appear without valid reason after attendance was requested, unless exceptional circumstances justify another result.

The tribunal should consider:

• Health;
• Travel restrictions;
• Visa difficulties;
• Employment restrictions;
• Whether remote testimony is available;
• Whether the witness is under the party’s control;
• Whether the opposing party will be prejudiced.

A party should not rely on a detailed written statement while preventing the opposing party from testing that evidence through questioning.

Remote Witness Hearings

Witnesses and experts may participate through video conference.

ISTAC’s Online Hearing Rules permit hearings and meetings to take place through video or teleconference. They require the tribunal to consult the parties regarding technology, confidentiality and technical arrangements. Witnesses and experts must appear visibly on camera, and the tribunal controls which documents may be made available during testimony.

A remote-hearing protocol may address:

• Camera positioning;
• Identity verification;
• Room inspection;
• Prohibition of unauthorised persons;
• Document access;
• Messaging restrictions;
• Backup connections;
• Time zones;
• Interpretation;
• Recording;
• Cybersecurity.

The 2020 IBA Rules also recognise remote evidentiary hearings and recommend protocols designed to ensure fairness, technological reliability and protection against improper influence.

The tribunal should ensure that remote testimony does not impair the right to be heard.

Expert Evidence

Expert evidence is used where the tribunal requires specialised knowledge beyond ordinary legal and commercial assessment.

Experts may be required in disputes involving:

• Construction delay;
• Engineering;
• Product defects;
• Accounting;
• Company valuation;
• Lost profits;
• Banking;
• Energy markets;
• Information technology;
• Intellectual property;
• Foreign law;
• Medical or scientific issues.

Turkish arbitration law recognises two principal models:

• Experts appointed by the parties;
• Experts appointed by the tribunal.

Article 12 of International Arbitration Law permits the tribunal to appoint one or more experts, require the parties to provide explanations and documents and order an inspection. The parties may question the tribunal-appointed expert and present their own experts.

The domestic arbitration provisions contain substantially parallel rules.

Party-Appointed Experts

A party-appointed expert is selected and instructed by one party.

The expert may analyse:

• Technical responsibility;
• Delay;
• Quantum;
• Valuation;
• Foreign law;
• Industry practice;
• Accounting records.

Although appointed and paid by one party, the expert should provide an independent professional opinion rather than act as an advocate.

A persuasive expert report should disclose:

• The expert’s qualifications;
• Relationships with the parties and counsel;
• Instructions;
• Assumptions;
• Factual sources;
• Methodology;
• Calculations;
• Limitations;
• Conclusions;
• Documents relied upon.

The IBA Rules require a party-appointed expert report to identify the expert’s relationships, qualifications, instructions, independence, factual basis, methodology, supporting documents and genuine belief in the opinions expressed.

An expert who ignores unfavourable records, adopts counsel’s argument without technical analysis or refuses to acknowledge obvious limitations may lose credibility.

Tribunal-Appointed Experts

The tribunal may appoint its own independent expert where specialist assistance is required.

Before appointment, the tribunal should define the expert’s terms of reference and give the parties an opportunity to comment on:

• Qualifications;
• Independence;
• Scope of work;
• Questions to be answered;
• Documents and materials;
• Inspection procedure;
• Fees.

Under the IBA Rules, a tribunal-appointed expert must disclose qualifications and independence. The parties may object, review materials examined by the expert, respond to the report and question the expert at the hearing.

The tribunal-appointed expert does not replace the tribunal.

The tribunal must independently assess:

• Methodology;
• Assumptions;
• Consistency;
• Responses to criticism;
• Other expert evidence;
• The complete factual record.

The award should not merely reproduce the expert report without demonstrating that the tribunal considered the parties’ submissions.

Expert Meetings and Joint Statements

Where opposing experts address the same issues, the tribunal may order them to meet.

The experts may be asked to prepare a joint statement identifying:

• Matters agreed;
• Matters disputed;
• Reasons for disagreement;
• Different assumptions;
• Different methodologies;
• Additional information needed.

This process can narrow the technical dispute and allow the hearing to focus on the genuine areas of disagreement.

The IBA Rules expressly permit the tribunal to order party-appointed experts to meet, attempt to reach agreement and record both agreed and disputed matters.

Expert meetings should not be used to pressure an expert into abandoning an honestly held opinion.

Expert Conferencing or “Hot-Tubbing”

Expert conferencing allows experts to give evidence together.

The tribunal may ask both experts the same question and allow them to respond to each other directly.

This technique may be particularly effective where the dispute concerns:

• Delay methodology;
• Valuation assumptions;
• Engineering standards;
• Accounting treatment;
• Technical causation.

The IBA Rules permit the tribunal to arrange testimony by issue and question witnesses or experts simultaneously in confrontation with each other.

Expert conferencing may reveal differences more clearly than conventional sequential cross-examination.

However, the tribunal should establish an orderly process to ensure that the more assertive expert does not dominate the discussion.

Physical Inspection and Site Visits

Some disputes cannot be resolved through documents alone.

Inspection may be required for:

• Construction sites;
• Machinery;
• Manufacturing facilities;
• Defective products;
• Samples;
• Software systems;
• Inventory;
• Physical damage.

Article 12 of International Arbitration Law allows the tribunal to order an inspection.

The tribunal should determine:

• Location;
• Timing;
• Participants;
• Photography;
• Sampling;
• Testing;
• Safety;
• Confidentiality;
• Preservation of the inspected material;
• Reporting.

Both parties should ordinarily receive an opportunity to attend or be represented.

The IBA Rules likewise allow the tribunal or experts to inspect property, machinery, goods, samples, systems, processes or documents, with the parties having a right to attend.

Judicial Assistance in Collecting Evidence

An arbitral tribunal lacks direct coercive authority over many third parties.

A non-party may refuse to:

• Produce documents;
• Attend voluntarily;
• Permit an inspection;
• Provide records;
• Cooperate with an expert.

Article 12 of International Arbitration Law permits the tribunal to request assistance from the competent Turkish court in collecting evidence.

For domestic arbitration, a party may seek court assistance with the tribunal’s approval under Article 432 of the Code of Civil Procedure.

Court assistance may be relevant where evidence is held by:

• Banks;
• Former employees;
• Public bodies;
• Service providers;
• Independent contractors;
• Corporate affiliates not bound by the arbitration agreement.

The request should identify:

• The precise evidence;
• The person holding it;
• Relevance and materiality;
• Why voluntary production is unavailable;
• The tribunal’s approval or request.

The court assists with collection. It does not decide the evidential weight or the merits of the arbitration.

Failure to Produce Evidence

A party’s refusal to produce ordered evidence may have serious consequences.

Under International Arbitration Law, if a party fails without valid reason to attend a hearing or submit evidence, the tribunal may continue the proceedings and decide on the existing record.

Where the IBA Rules apply, the tribunal may infer that an unjustifiably withheld document or other evidence would have been adverse to the withholding party. It may also consider bad-faith evidentiary conduct when allocating arbitration costs.

An adverse inference should not be automatic.

The requesting party should ordinarily establish that:

• The evidence probably exists;
• It is within the other party’s control;
• It is relevant and material;
• Production was requested properly;
• No satisfactory explanation was provided.

The tribunal should explain the inference in its reasoning and avoid using it as a substitute for the claimant’s basic burden of proof.

Admissibility and Weight of Evidence

Admission of evidence and evaluation of its weight are separate questions.

A tribunal may admit evidence but give it limited weight because:

• It is hearsay;
• It was created after the dispute;
• Its author was unavailable;
• Its authenticity is doubtful;
• It conflicts with contemporaneous records;
• It is based on assumptions;
• The expert lacks independence.

The IBA Rules expressly provide that the tribunal determines the admissibility, relevance, materiality and weight of evidence.

Arbitration generally favours flexible admission combined with careful evaluation. This can be more efficient than excluding evidence solely because it would face a formal objection in ordinary court litigation.

Flexibility must not undermine equality or the right to respond.

Translation of Evidence

The language of arbitration determines whether translations will be required.

Article 10 of International Arbitration Law permits the tribunal to require documents to be submitted with translations into the language or languages of the arbitration.

The tribunal may allow untranslated documents where:

• Both parties understand the original language;
• The document is straightforward;
• Translation would be disproportionately expensive;
• Only relevant extracts require translation.

The tribunal should avoid creating procedural inequality.

Important documents such as:

• The contract;
• Critical correspondence;
• Expert reports;
• Witness statements;
• Operative regulatory documents,

should ordinarily be available in a language understood by the tribunal and opposing party.

Equality and the Right to Be Heard

Evidentiary flexibility is limited by procedural fairness.

Each party must receive:

• Notice of the evidence relied upon;
• A reasonable opportunity to respond;
• Access to material submissions;
• An opportunity to question important witnesses and experts where appropriate;
• Equal procedural treatment.

International Arbitration Law requires submissions, information and documents given to the tribunal to be communicated to the opposing party. Hearings, inspections and expert examinations must be notified sufficiently in advance.

Domestic arbitration contains parallel protections.

A tribunal should be cautious about relying on:

• Undisclosed documents;
• Private communications with an expert;
• Evidence submitted after closure;
• Independent research not disclosed to the parties;
• New legal or factual theories on which the parties were not heard.

Evidence-Related Grounds for Setting Aside an Award

An arbitral award should not be set aside merely because a court would have evaluated the evidence differently.

The setting-aside court is not an appellate tribunal reviewing witness credibility, expert methodology or ordinary factual findings.

However, serious evidentiary unfairness may support an annulment application where:

• One party was denied a meaningful opportunity to present evidence;
• Material evidence was withheld from one party;
• The tribunal relied on undisclosed evidence;
• One party was allowed to call witnesses while the other was denied an equivalent opportunity without justification;
• A material procedural agreement was disregarded;
• The right to be heard or equality was violated.

For domestic arbitration, Article 439 permits annulment where the agreed or statutory procedure was materially violated or equality and the right to be heard were not respected.

International Arbitration Law contains corresponding protections through its limited annulment grounds.

A party should raise procedural objections promptly during the arbitration. Remaining silent and raising the issue only after an unfavourable award may create waiver arguments.

Practical Evidence Strategy

A party preparing for Turkish arbitration should:

• Preserve documents immediately;
• Suspend automatic deletion;
• Identify key witnesses;
• Create a factual chronology;
• Review contractual notice requirements;
• Determine the burden of proof;
• Identify evidentiary gaps;
• Consider document production needs;
• Engage experts early where necessary;
• Preserve physical evidence;
• Investigate authenticity issues;
• Plan translations;
• Consider third-party court assistance;
• Prepare witnesses honestly;
• Test expert assumptions;
• Comply strictly with procedural deadlines.

The evidence should support a clear factual theory.

A successful case is not created by submitting the greatest number of documents. It is created by showing how reliable documents, credible witnesses and sound expert analysis establish each required element of the claim or defence.

Frequently Asked Questions

Does Turkish civil procedure apply automatically to evidence in international arbitration?

No. The parties may determine the procedure within the limits of mandatory law. In the absence of agreement, the tribunal applies the International Arbitration Law and conducts the proceedings with significant procedural flexibility.

Can the tribunal refuse late evidence?

Yes. The tribunal may manage the timetable and may reject late evidence where admission would cause unfairness, excessive delay or procedural disruption.

Is document production available in Turkish arbitration?

Yes. The parties may agree on document production rules, and the tribunal may establish a targeted production procedure. The IBA Rules are frequently used as a model but apply only where adopted or used as guidance.

Can company employees testify?

Yes. A party, director, employee or representative may give factual evidence. Their connection to the party affects credibility and weight rather than automatic admissibility.

Are written witness statements permitted?

Yes. Written statements are widely used and may serve as direct testimony, subject to questioning at the hearing where attendance is requested.

Can counsel prepare a witness?

Counsel may interview the witness, discuss prospective testimony and explain the procedure. Counsel must not induce false testimony or replace the witness’s own recollection.

Is cross-examination mandatory?

Not in every case. The procedure depends on the parties’ agreement and tribunal orders. Where a material witness’s attendance is requested, the opposing party should ordinarily receive an opportunity to question that witness.

Can witnesses testify remotely?

Yes. ISTAC’s Online Hearing Rules expressly permit witnesses and experts to participate by video conference or video call, subject to tribunal control and procedural safeguards.

Can each party appoint its own expert?

Yes. Turkish arbitration law permits the parties to present their own experts even where the tribunal also appoints an expert.

Is the tribunal bound by its appointed expert?

No. The tribunal must assess the expert report together with the complete evidentiary record and the parties’ objections.

Can experts be heard together?

Yes. The tribunal may order expert meetings, joint statements or simultaneous testimony through expert conferencing.

Can a Turkish court compel a third party to produce evidence?

Court assistance may be requested where the legal requirements are satisfied and the tribunal has approved or requested assistance.

What happens if a party refuses to produce an ordered document?

The tribunal may continue the case, draw an adverse inference where appropriate and consider the conduct when allocating costs.

Can illegally obtained evidence be used?

The answer depends on the circumstances and applicable procedural framework. Under the IBA Rules, the tribunal may exclude illegally obtained evidence.

Can an award be annulled because the tribunal evaluated evidence incorrectly?

An ordinary disagreement with evidentiary weight is generally not sufficient. Annulment may become relevant where serious procedural violations affect equality, the right to be heard or compliance with the agreed procedure.

Conclusion

Evidence, witnesses and expert reports are central to the outcome of Turkish arbitration proceedings.

Turkish arbitration law gives the parties and tribunal substantial flexibility. The process does not automatically reproduce every evidentiary formality applied in ordinary Turkish court litigation.

The parties may agree on institutional rules, international evidentiary standards or a bespoke procedure. The tribunal may determine the timetable, hold oral or document-only proceedings, appoint experts, conduct inspections and request court assistance.

This flexibility is subject to fundamental safeguards. Each party must receive equal treatment, access to material evidence and a genuine opportunity to present and test the opposing case.

Documentary evidence should be organised, relevant and connected to the disputed issues. Document production should remain targeted and proportionate. Broad discovery requests are generally less suitable than requests identifying specific documents or narrow categories that are material to the outcome.

Witness statements should reflect the witness’s own knowledge rather than legal submissions prepared by counsel. Cross-examination should test reliability and credibility fairly.

Expert evidence should identify assumptions, methods, data and limitations transparently. Party-appointed experts should maintain professional independence, while tribunal-appointed experts must remain subject to party comment and questioning.

Electronic evidence requires particular care. Native files, metadata, message histories and digital systems may provide information that cannot be seen in printed copies. Parties should preserve such evidence as soon as a dispute becomes foreseeable.

Where third parties hold evidence or refuse to cooperate, Turkish courts may provide assistance within the statutory framework. Court involvement remains supportive: the tribunal decides relevance, weight and the merits.

The strongest arbitration strategy begins before proceedings are commenced. Businesses should maintain reliable records, document contractual notices, preserve electronic material and establish internal evidence-retention procedures.

Once a dispute arises, counsel should identify the required factual propositions, allocate the burden of proof and construct a focused evidentiary plan combining documents, witnesses and expert analysis.

A legally persuasive argument unsupported by evidence will rarely succeed. Conversely, a well-organised factual record supported by credible testimony and transparent expert analysis can substantially improve the effectiveness, efficiency and enforceability of Turkish arbitration proceedings.

Legal Disclaimer: This article is provided for general informational purposes only and does not constitute legal advice. Evidentiary procedure depends on the arbitration agreement, seat, applicable law, institutional rules, tribunal orders, nature of the dispute and evidence involved. Case-specific advice should be obtained before submitting or challenging evidence in arbitration.