1. Legal Basis and Purpose of Expert Opinions in Judicial Proceedings
The institution of expert witnessing serves as a judicial aid that allows the court to seek technical, scientific, or specialized knowledge in complex matters beyond the judge's general legal expertise. This necessity is firmly established under Article 266 of the Turkish Code of Civil Procedure (Law No. 6100, hereinafter “CCP”):
“The court may refer the matter to an expert in cases that require special or technical knowledge outside the scope of the law.”
This provision confirms that expert reports serve a supportive and auxiliary role. The judge retains full authority and responsibility to evaluate legal issues; this duty cannot be delegated to the expert.
Expert witnessing also serves a crucial function in ensuring fair trials by assisting judges in understanding technical evidence or data that would otherwise be beyond their capacity.
2. Scope of Authority: The Prohibition on Legal Assessment by Experts
One of the most fundamental limitations of the expert's role is the prohibition from making legal evaluations. Article 267 of the CCP explicitly states:
“Experts shall not be consulted in matters that require legal knowledge.”
Accordingly, an expert may not:
Assess whether a contract is valid or invalid,
Comment on the existence of legal liability,
Interpret legal norms or assign legal consequences to facts.
These are strictly within the authority of the judge. If an expert includes legal conclusions such as “The defendant is liable and must compensate,” this constitutes ultra vires and renders the opinion legally inadmissible.
Example of an Improper Legal Conclusion:
“Since the respondent breached the contract, they are liable for damages.” This constitutes a legal opinion and is therefore outside the expert’s remit.
3. Evidentiary Value: Are Expert Reports Binding on the Court?
Under Turkish procedural law, expert reports are discretionary evidence. They assist the judge in forming an opinion but are not binding. Article 282 of the CCP provides:
“The court is not bound by the expert’s opinion. If the judgment relies on the expert report, the court must explicitly state the grounds for agreeing with it.”
Thus, a judge must:
Freely evaluate the report,
Justify any decision based on it,
Not treat the report as a conclusive or determinative source of evidence.
Court of Cassation Precedents:
15th Civil Chamber, E. 2019/3211, K. 2020/1953
“Legal conclusions drawn by the expert are not binding on the court. The judge must form their own legal judgment.”
General Assembly of Civil Chambers, E. 2017/9-1052, K. 2019/143
“If a court bases its decision on the expert report, it must clearly explain why the expert’s opinion was adopted.”
4. Objection to Expert Reports and Request for a New Evaluation
Pursuant to Article 281 of the CCP, parties have the right to object to expert reports. Grounds for objection may include:
Type of Deficiency
Technical insufficiency: Lack of reasoning, superficial analysis, or missing data
Legal interpretation: Expert goes beyond technical assessment into legal conclusions
Internal or external contradiction: Report conflicts with itself or other evidence in the file
Bias or impartiality concerns: Alleged connections between expert and one of the parties
If objections are found to be valid, the court may:
Assign a new expert,
Request an additional report,
Disregard the existing report when forming the judgment.
Example Ruling:
“If the expert report is found to be inadequate, the court must obtain a supplementary or second opinion. Rendering a decision without resolving this deficiency is grounds for reversal.” (Court of Cassation, 22nd Civil Chamber, E. 2020/245, K. 2021/399)
5. Consequences of Legal Evaluation by the Expert
If an expert makes legal assessments in violation of the law, the affected portions of the report are:
Legally inadmissible, and
Cannot serve as grounds for judgment.
In some cases, the court may face reversal if it relies on such conclusions.
Precedent: Court of Cassation, 12th Civil Chamber, E. 2021/4571, K. 2022/3593
“An expert's opinion on the validity of a contract constitutes a legal judgment and must be disregarded in forming the court’s decision.”
6. Are Expert Reports Sufficient Grounds for Judgment Alone?
No. Expert reports are not sufficient in themselves to support a final ruling. They must be:
Evaluated together with all other evidence,
Supported by concrete factual findings,
Part of a holistic assessment of the case.
If a court bases its decision solely on the expert report without proper justification or reasoning, this may be seen as an abdication of judicial duty and result in annulment of the decision on appeal.
7. Conclusion and Final Remarks
Expert reports are non-binding advisory tools used in technical matters requiring specialized knowledge. They:
✅ Aid the court with technical data and analysis, ❌ Do not bind the judge, ❌ Cannot include legal assessments, ✅ May be challenged by the parties, ✅ Must be justified if relied upon in a judgment, ❌ Cannot be the sole basis for a court ruling.
The role of the judge remains central, and expert opinions serve only to inform—not determine—the legal outcome.
Frequently Asked Questions
Are expert reports conclusive evidence? No. They are advisory and do not bind the court.
Can an expert give a legal opinion? No. Experts are prohibited from making legal assessments.
What happens if the expert report is flawed? Parties may object, and the court may order a new report.
Must the judge follow the expert’s opinion? No. But if they do, they must provide clear reasoning.