What is expert testimony?

1. Introduction

In modern legal systems, expert opinion is essential for the fair and accurate conduct of trials . Since judges cannot be experts in every field, the institution of expert witnesses comes into play in situations requiring specialized or technical knowledge .

In Turkish law, expert testimony to ensure the proper administration of justice and to support the judge's decision with scientific or technical data. However, the accuracy, impartiality, and impact of expert reports on the trial have always been subjects of debate.

2. The Concept of Expert Witnessing and its Legal Basis

Expert testimony is regulated by Articles 266-287 of the Code of Civil Procedure (Law No. 6100) , Articles 63-71 of the Code of Criminal Procedure (Law No. 5271) , and the Expert Testimony Law No. 6754

Definition: A process by which judges, in cases requiring specialized or technical knowledge, consult with individuals or legal entities who are experts in the field to provide their opinions.

Important Note: The expert witness does not replace the judge in the trial; they only provide the judge with technical information. The final decision always rests with the judge.

3. Types of Expert Witness Testimony

Expert testimony takes different forms depending on the need:

Forensic expert testimony: Experts appointed by courts, prosecutors' offices, and enforcement offices.
Party expert opinion: Private reports prepared by the parties at their own request (not considered mandatory by the court).
Institutional expert opinions: Expert reports from official institutions (forensic medicine, criminal laboratory, etc.).

4. The Process of Preparing the Expert Report

An expert report is critical evidence in a trial and goes through the following stages:

Appointment of expert witnesses – The judge appoints expert witnesses in matters requiring technical or specialized knowledge.
Examination and assessment – The expert examines the file and necessary documents and conducts an on-site assessment.
Report preparation – A reasoned report is prepared in light of scientific and technical data.
Notification to the parties – The report is notified to the parties to allow them the right to object.
Court assessment – The judge will evaluate the report in conjunction with other evidence; they cannot rely solely on the report.

5. Objection to the Expert Report

Legal Basis:

HMK Article 281
CMK Article 67

The parties may object to the expert report within two weeks of its notification . Objections may be made in the following ways:

The claim that the report is incomplete or inaccurate.
The claim is that scientific data has been misinterpreted.
Allegations of violation of the principle of neutrality.
Request for the appointment of a new expert witness.

the court finds the objection justified, it may decide to obtain an additional report or appoint a new expert.

6. Expert Testimony in Light of ECHR Judgments

The European Court of Human Rights (ECtHR) considers expert reports within the scope of the right to a fair trial

Basic Principles:

The parties should be informed of the expert report's contents and have the right to submit counter-arguments.
The impartiality of the expert witness is as important as the independence of the judiciary.
The judge must critically evaluate the expert report and not automatically accept it.

Example of a ECHR decision:

Sara Lind Eggertsdóttir / Iceland case – The court considered the expert's conflict of interest with one of the parties as a violation of the right to a fair trial.

7. Court of Appeals Practice

The Supreme Court's established jurisprudence has a clear approach to expert reports:

The judge cannot accept the expert report as the sole and conclusive evidence
The report should be evaluated in conjunction with other evidence.
Issuing a judgment without considering the objections of the parties is contrary to procedure and law.

The Supreme Court also considers it grounds for annulment if an expert prepares a report outside their area of expertise.

Impartiality of the Expert Witness:
It is contrary to the principle of impartiality for an expert witness to also be technically responsible in the same case. Rendering a judgment based on such an expert report is unlawful. (Supreme Court of Appeals, 18th Criminal Chamber, 2019/5310)

Abuse of Office
by an Expert Witness: Giving a false opinion as an expert witness in an institution that is not a judicial body constitutes the crime of abuse of office under Article 257/1 of the Turkish Penal Code. (Supreme Court of Appeals, 9th Criminal Chamber, 2014/7161)

The Necessity of Resolving Conflicting Expert Reports:
If there are conflicting expert reports regarding whether an artifact is a cultural heritage site, a new report must be obtained from a panel of expert witnesses. (Supreme Court of Appeals, 12th Criminal Chamber, 2015/4047)

Determining Fault Based on Expert Reports:
In cases where there are conflicting expert reports regarding fault percentages in a traffic accident, it is unlawful to issue an acquittal without obtaining an additional report from an expert institution. (Supreme Court of Appeals, 12th Criminal Chamber, 2016/12420)

The need to obtain an additional expert report
constitutes grounds for reversal if a decision is made without clearly determining the nature of the zoning violation and without obtaining an additional expert report. (Supreme Court of Appeals, 4th Criminal Chamber, 2015/2189)

Obligation to Conduct Expert Examination:
If the similarity of signatures necessitates a technical examination, a conviction cannot be rendered without conducting an expert examination. (Supreme Court of Appeals, 10th Criminal Chamber, 2008/9365)

Obtaining an Expert Report in Embezzlement Cases:
Given the conflicting reports regarding embezzlement in the cooperative, a new report should be obtained from an expert panel composed of legal and financial specialists. (Supreme Court of Appeals, 5th Criminal Chamber, 2014/6512)

The Importance of Expert Reports in Illegal Electricity Use:
An additional expert report should be obtained to accurately calculate the damages, and if compensation is paid, the provisions for effective repentance should be applied. (Supreme Court 17th Criminal Chamber, 2017/13522)

Objection to the Forensic Medicine Report and the Establishment of a New Expert Board:
If the forensic medicine report is insufficient, a new report should be obtained from an expert board composed of specialists from the relevant fields. (Supreme Court of Appeals, 13th Civil Chamber, 2020/5453)

8. Current Issues

Some prominent problems in the expert witness system are as follows:

The issue of impartiality – Some experts being linked to the parties involved.
Lack of expertise – Appointing individuals who are not knowledgeable about the subject.
Excessive reporting workload – Experts are unable to conduct detailed examinations due to being assigned to numerous cases.
Non-standard reports – Reports that lack a scientific basis or justification.

9. Proposed Solutions

Regular updating of expert witness lists.
When making appointments, the connection between the area of expertise and the subject matter should be strictly checked.
More effective use of the parties' right to question the expert.
Increasing performance monitoring in expert witness cases.

10. Conclusion

Expert testimony is an integral part of a fair trial. However, the non-binding nature of the report, the judge's obligation to make an independent assessment, and the parties' effective right to object are guaranteed by both national law and the case law of the European Court of Human Rights.

Right to a fair trial, expert report, objection to expert report.

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