Can email/WhatsApp correspondence be used as evidence in a commercial lawsuit?

Evidential Value, Probabilistic Value, Presentation and Objection Strategy (2026) (From a Procedural Perspective)

According to Article 199 of the Turkish Commercial Code, are email/WhatsApp communications considered "documents"? What is their value in the face of the rule of proof by written document? The prohibition of illegally obtained evidence, the difference between KEP (Registered Electronic Mail) and e-signature, presentation and expert examination practices are discussed in this article.

Commercial life has long since shifted to the practice of "contract formation and performance through correspondence." Orders, revisions, deadlines, price agreements, notifications of defects, termination/default notices, current account confirmations... Many critical steps are now conducted via email and messaging channels. But can this correspondence really be considered evidence in a commercial court ?

Answer: Yes, it's possible — but not always with the same probative value. In procedural law, the issue isn't resolved with the simplistic notion that "what's displayed on the screen is evidence"; rather the distinction between documents and promissory notes, the rule of proof by promissory notes, the prohibition of illegally obtained evidence, verification/determination in cases of denial, and the manner in which evidence is presented .

1) Legal basis: Do electronic data count as "documents"?

(HMK) abandoned the traditional understanding of "paper" and broadened the definition of "document. Articlenot only written/printed texts suitable for proving the facts in dispute, but data in electronic form as "documents." Therefore, e-mail and messaging records are, as a rule, documents within the meaning of HMK Article 199.

This observation is important because being a "document" does not automatically mean that the evidence conclusive . The probative valueis subject to the following two major filters:

1. the requirement to prove something with a written document (Code of Civil Procedure, Article 200) being applied?

2. the evidence lawfully ? (Code of Civil Procedure, Article 189/2)

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2) A critical distinction in commercial litigation: “Document” ≠ “Promissory Note” (written evidence)

2.1. What does the rule of proof by written document (Code of Civil Procedure, Article 200) do?

For certain legal transactions and claims exceeding specific monetary thresholds, the Code of Civil Procedure introduces the "proof by written document" system. This means that written evidence/document is required to prove your claim; relying solely on witness testimony becomes difficult.

At this point, email/WhatsApp communication is often:

• It is not valid as a promissory note (especially if it does not have a secure electronic signature),

• However, initial evidence plus supplementary evidence (business ledgers, bank records, invoices/delivery notes, delivery receipts, HTS/courier records, witnesses, etc.) can strengthen the claim.

2.2. “Initial evidence” (Code of Civil Procedure, Article 202) and digital correspondence

Article 202 of the Code of Civil Procedure initial written evidence " in cases where proof by written document is required. Digital correspondence, especially to the extent that the other party does not "completely deny" it or that it contains content indicating the existence of a relationship/transaction between the parties, can function as "initial evidence" in practice.

Practical takeaway: In commercial litigation, email/WhatsApp is often not the "sole conclusive evidence"; one of the pillars supporting the case .

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3) Email correspondence: Can be used as evidence, but "originality" and "completeness" are required

3.1. In what situations is email considered strong evidence?

An email is considered a document within the meaning of Article 199 of the Turkish Code of Civil Procedure.
However, the following factors increase its probative value:

• Corporate email infrastructure (domain-based company email, server logs, standard signature, authorized person's role)

• The raw format of the email (such as EML/MSG; header information)

• Supported by system records (CRM records, order system, accounting vouchers, bank transactions)

• Clear agreement on the content (price, deadline, delivery terms, "acceptance" statement, unquestioning confirmation)

In this context the Supreme Court's jurisprudence indicating that e-mail correspondence should be evaluated within the scope of Article 199 of the Code of Civil Procedure.

3.2. The risk of "Forward" and screenshots

Only "forwarded" emails or screenshots their modifiability . If the other party denies it, the court will usually:

• the raw email file,

• server logs,

• It considers expert examination when necessary
  

Procedural message: When using email as evidence, your goal is not simply to "show the text"; it is to include technical evidence demonstrating the email's existence and integrity in the file

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4) WhatsApp conversations: These are documents; verification is required if there is a denial

4.1. Are WhatsApp logs considered "documents"?

Since Article 199 of the Turkish Code of Civil Procedure considers electronic data as documents, it is possible to present messaging records as evidence.
However, the main issue in applications like WhatsApp over who wrote the message and whether it has been subsequently altered .

4.2. Is a screenshot sufficient on its own?

Screenshot in the app:

• evidence at first glance ,

• However, if the other party says "I didn't write it / this speech isn't mine / it's a montage," the court often needs technical verification

What are the key aspects of this verification?

• Forensic analysis of the device containing the recorded conversation (image acquisition, hashing, integrity),

• Chat export logs,

• phone number – line ownership – device matching,

• Consistency with other evidence (payment receipt, delivery note, email, ledger entry)

In legal doctrine and case summaries, it is stated that message outputs whose accuracy/authenticity cannot be demonstrated may not even be considered "initial evidence"; technically verifying attribution is critical.

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5) The strictest filter: Prohibition of illegally obtained evidence (Code of Civil Procedure, Article 189/2)

This is where the debate over "digital evidence" in commercial litigation was broken.

Article 189/2 of the Code is clear: Evidence obtained unlawfully cannot be taken into account in proving a fact.

This rule is read in conjunction with the constitutional protection of communication and privacy. The Constitutional Court's jurisprudence also emphasizes the protection of the confidentiality of communication, presenting a perspective that includes postal and electronic mail.

5.1. Examples of illegality in commercial litigation (risk areas)

• the other party's email account without authorization and retrieving their correspondence.

• Unauthorized retrieval of messages from someone else's phone/WhatsApp

• Obtaining data through methods such as spyware, covert surveillance, and password cracking

• "Secret recording" and similar serious interventions (to be evaluated separately on a case-by-case basis)

Practical warning: "Accurate content" isn't always enough; even the strongest piece of evidence can be dismissed in a commercial lawsuit if its acquisition method was illegal .

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6) Presenting evidence correctly: Procedural roadmap in commercial litigation

6.1. When should evidence be presented?

In the HMK (Code of Civil Procedure) system, it is essential that evidence supporting the claims and defenses at the petition stage . (List of evidence in the lawsuit/response petition; attachments if possible.) The general logic of the HMK is to reduce surprises in the trial.

Therefore, the approach of "I will submit the WhatsApp printout later with an additional application" creates unnecessary risk in most cases.

6.2. How to present it? (A compelling format for the file)

For email:

• The email content + date/time + sender/recipient are clearly visible in the output

• If possible, a format that preserves the raw file (EML/MSG) and technical header information

• "Matching evidence package" along with relevant payment/delivery/confirmation documents

For WhatsApp:

• Chat screenshot (not to be left alone)

• Chat export output

• Additional evidence demonstrating number/line ownership and commercial relationship

• If there is a possibility of denial, a scenario prepared for an early request for technical review.

6.3. What happens if the other party denies it?

Denial, procedurally, triggers a debate about "the attribution and integrity of the evidence.".

The court in this case:

• expert examination

• device review,

• Comparing the records,

• supporting evidence in the file
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At this point, your strategy should be:

• Instead of saying, "I have evidence,"

• "This evidence a verifiable technical basis."

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7) The most secure channel: KEP and secure electronic signature

In commercial relationships, especially in critical notifications such as warnings/notices/terminations/defaults, two tools stand out as fundamentally resolving the issue of "proof":

1. Secure electronic signature: According to Law No. 5070, a secure electronic signature has the same legal effect as a handwritten signature.

2. Registered Electronic Mail (KEP): The system generates evidence records regarding processes such as sending, delivery, and reading; this area is regulated by regulation.

Furthermore, the Turkish Commercial Code explicitly states that certain notifications and warnings between merchants can be made via KEP (Registered Electronic Mail) using secure electronic signatures

Procedural conclusion:
While regular email and WhatsApp are considered "disputed documents," the combination of KEP (Registered Electronic Mail) and e-signature narrows the scope of evidence dispute in most cases.

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8) Practical scenarios in commercial litigation

Scenario A: “The order was placed via WhatsApp, an invoice was issued, but payment was not made.”

• WhatsApp conversation: evidence of the order's existence

• Invoice/delivery note: delivery/payment element

• Bank transactions: partial payments strengthen the relationship.
  This combination prevents WhatsApp from being "alone" and facilitates the transfer of the file.

Scenario B: “Price/delivery time confirmed via email, then they say 'I didn't accept it'."

• Email content + header/raw record + corporate email infrastructure

• Subsequent performance steps (shipment, warehouse acceptance, payment)
  In case of denial, the technical trace of the email and the performance behavior are evaluated together.

Scenario C: "Evidence exists, but it was obtained illegally."

Article 189/2 of the Code of Civil Procedure comes into play; the court may disregard the evidence.
Therefore, in commercial disputes, the "method of obtaining evidence" must be clean from the outset.

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FAQ

1) Can a court consider a WhatsApp conversation as conclusive evidence?
It can generally be presented as "evidence"; however, denial raises a debate about its authenticity/integrity, increasing the need for technical verification.

2) Can an email serve as a substitute for a promissory note?
In most cases, it may not function as a "promissory note" unless secure electronic signatures/REGISTERED electronic mail are available; however, it can establish a strong basis for proof when combined with other evidence.

3) Is submitting a screenshot sufficient as evidence?
It can be submitted initially; however, if denied, a technical examination and supporting evidence will be required.

4) What if I obtain and present the other party's email/WhatsApp without permission?
According to Article 189/2 of the Code of Civil Procedure, this creates a risk of violating the prohibition against presenting illegally obtained evidence; the court may not consider the evidence.

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Email and messaging records have become so central to commercial litigation that they can no longer be dismissed as "not evidence." Article 199 of the Code of Civil Procedure recognizes electronic data as documents; this means that emails/WhatsApp can be included in the file.
However, the real struggle the rule of proof by written document, of initial evidence , verification in case of denial , and, most importantly, the prohibition of illegally obtained evidence .