Opinion of the Court of Cassation on the Contention of Expert Opinion and Expert Report
"Expert Opinion” in Short
The notion of Expert Opinion, which entered into our law through the Code of Civil Procedure ("CCP"), has been a frequently resorted to method of helping to resolve disputes by the parties in our judicial system over the course of time. Expert opinion, which is the reflection of the Anglo-Saxon Law concepts, "party expert" or "expert witness" in our legal system, is defined in Article 293 of the CCP:
- The parties may obtain scientific opinion from an expert in relation to the subject of the case. Extra time cannot be requested solely based on this purpose.
- The judge may decide, upon receipt of the request, or ex officio, to call the expert who has prepared the report to the hearing, and to listen to him/her. The judge and the parties may ask pertinent questions when the expert is called.
- If the expert does not appear at the hearing without a valid reason, the report that he/she has prepared shall not be evaluated by the court.
For more detailed information on this topic, you can review our article called, “An Important Innovation Brought by the New Civil Procedure Law: Expert Opinion.”
Throughout the course of the proceedings, parties may submit an opinion from an expert to the court relating to the event or legal matter constituting the issue of dispute, in order to support their claims or defenses. The expert opinion is, at times, presented during the phase of exchange of petitions, and sometimes during the inquiry, especially after the expert investigation, by the party for whom the expert report contains unfavorable analysis and comments.
In accordance with Article 266 of the CPP, the court may decide that there shall be an expert investigation regarding the case, and the opinion of the expert shall be taken regarding the subject of investigation, where the solution of the dispute requires special and technical knowledge other than the law, upon the request of one of the parties, or ex officio.
The expert opinion presented to the file in the course of the proceedings is, to a large extent, supportive of the party that is presenting the opinion. As a natural consequence, the expert opinion presented by one of the parties may contain opposing views and even completely contradict the opinion of the expert report that is already filed with the court. At this stage, it is a matter of debate whether or not the investigation shall be finalized and the case decided, according to the opinion of the court, or whether a new expert examination is to be sought.
What is the Solution of the Supreme Court in the Event of a Contradiction between the Expert Opinion and the Expert Report?
According to the decision of the 15th Civil Chamber of the Supreme Court, dated 10.11.2016 and numbered 2015/5127 E. 2016/4635 K., in the event of a contradiction between the expert opinion that is prepared as a result of the expert examination conducted by the court, and the expert opinion which is presented to the file by one of the parties, the file shall be delivered to a "new panel of experts," as the right to a fair trial of the party who presents the expert opinion to the file might be violated, otherwise:
"The case relates to the request of collection of the receivables arising from the defective manufacture under the contract of construction. In the event where one of the parties objects to the expert report in the file, based on the expert opinion, and these objections are not taken into account by the court, whatsoever, and are not responded to with justifications, the right to a legal hearing of the party that is dependent upon the expert opinion, which constitutes the most important element of the right to a fair trial that is protected under the Article 27 of the CCP numbered 6100, Article 36 of the Constitution, and Article 6 of the European Convention of Human Rights, shall be violated. The opinion of the expert submitted to the file contains findings and opinions contrary to the expert report, and there are serious contradictions between the expert report and the expert opinion. As it is incorrect to make a judgment on the basis of an inadequate and substantially challenged expert report, instead of having the file sent to a new expert committee in order to resolve the conflict between the expert report and the expert opinion, and evaluating and discussing this expert report with justification, the decision must be reversed.”
“… Defendant’s attorney has made substantial objections to the expert report and supported his objections by the expert opinion taken according to Article 293 of the CCP numbered 6100. The expert opinion, as regulated under Article 293 of the CCP numbered 6100, also referred to as the special expert in practice, is regulated as the parties’ way to obtain information from a special and technical expert determined by them, in order to enlighten and comprehend the case, and to prove their claims and defenses. The parties shall submit an expert opinion to the court in order to defend their interests and to shed light on the case in order to render a just and fair judgment, in the event they are not satisfied by the expert report taken by the court. In particular, the court is obliged to take into account and evaluate the expert opinion submitted by the party, if it is relevant to the case, where special and technical information is required … As it is incorrect to make a judgment on the basis of the inadequate and substantially challenged report, instead of having the file sent to a new expert committee in order to resolve the conflict between the expert report and the expert opinion, and evaluating and discussing this expert report with justification, the decision must be reversed.”
The 15th Civil Chamber of the Supreme Court ruled that it is compulsory to remove the contradiction between the expert report obtained by the court, and the expert opinion submitted by the party, and that this can only be resolved through the court ordering another expert report.
The Supreme Court has again made it clear that expert opinion cannot be excluded if it is contradictory to the court-appointed expert report. Where the parties object to the expert report based on expert opinion, the evaluation of these objections by the court is a requirement of the right to legal hearing.
The Court of Cassation has also linked taking a new expert report for the purpose of eliminating the contradiction between the expert report and the expert opinion, and evaluating the expert opinion with justifications, with the right to legal hearing. 
The Doctrine also defends that the Contradiction should be resolved through New Examination
This is also the point of view of in the doctrine. It is expressed that the procedure of hearing the expert by the court, where the expert answers the questions of the judges and the parties, is very important to reveal the impartiality and the scientificness of the expert opinion. In the event that the parties support their objection to the opinion of the expert appointed by the court with the report of an expert witness, the court should review the expert witness' report on a substantive basis, and should not prioritize the report of the expert witness appointed by the court without doing so. 
Although it is not possible to generalize, as is often the case in practice, courts hold expert opinions as secondary, while continuing review and rendering judgment on the basis of expert reports that are present in the file. However, the "Expert Opinion" concept defined in the CCP even allows the expert who gives the opinion to be summoned to the hearing and questioned, although this continues to exist in our judicial system as a method that is almost never resorted to. Nevertheless, the expert must be considered according to the clear provision of law, and in the event it is ruled that the expert is not to be heard, this decision must be justified. 
In conclusion, in the event that the present expert report in the file and the expert opinion submitted by one of the parties are contradictory, or contain opposing opinions, the court should form a new expert committee in order to eliminate the conflict between the expert report and expert opinion and, thus, finalize the judgment by thoroughly examining the claims and defenses of the parties, in a manner that makes it eligible for Supreme Court review.
 An Important Innovation Brought by the New Civil Procedure Law: Expert Opinion, May, 2011, http://www.erdem-erdem.av.tr/publications/law-post/an-important-innovation-brought-by-the-new-civil-procedure-law-expert-opinion/
 Prof. Dr. Mustafa Serdar Özbek, Law Journal numbered 2017/1 of the Union of the Turkish Public Notaries
 Prof. Dr. Baki Kuru - Prof. Dr. Ramazan Arslan - Prof. Dr. Ejder Yılmaz, Medeni Usul Hukuku Ders Kitabı, 22th Edition, Ankara, 2011, p. 456
 Dr. Cenk Akil, Medeni Yargılama Hukukunda Mahkeme Tarafından Atanan Bilirkişi-Uzman Tanık Ayrımı, Ankara Barosu Dergisi, 2011/2, p.175
 Prof. Dr. Hakan Pekcanıtez – Prof. Dr. Oğuz Atalay – Prof. Dr. Muhammet Özekes, Medeni Usul Hukuku, 14th Edition, p.799-800