Worldwide: Expert Witnesses In International Commercial Arbitration

Last Updated: 26 September 2016
Article by Mehveş Erdem

Most Read Contributor in Turkey, December 2017


In international arbitration, a party may submit evidence in different categories. Opinions of expert witnesses forms one of these categories. Expert opinions are mostly relied upon in complex cases that require special knowledge, such as construction, oil and gas, and insurance disputes, or in cases where damages quantum needs to be determined.

Expert witnesses can be appointed both by the parties and the arbitral tribunals. Most of the rules of the institutions allow tribunals to appoint expert witnesses. In practice, it is common for the parties to appoint their own experts and present expert report. In cases where the tribunal chooses to appoint an expert, it should set the boundaries of the expert's duty, and be careful not to delegate its own responsibilities to the expert. In some cases, the tribunal requests the parties to submit a list of experts over whom they can make a determination - this is most common in damages calculation.

Common and civil law traditions have different views as to expert evidence. Civil law practitioners are more suspicious when it comes to expert witnesses. This arises from the fact that in civil law traditions, the ordinary practice is for the court to appoint an independent expert.

Despite the different approaches in these two traditions, expert witnesses, today, depend on the subject matter of the dispute and specific circumstances, is considered to be a useful tool for both the parties and the tribunals.

Party Appointed Experts

Expert witnesses appointed by the parties in complex cases is one of the most common methods preferred by the parties and the tribunals. Pursuant to Article 5 of the IBA Rules on the Taking of Evidence in International Arbitration ("IBA Rules"), an expert report should contain the name, address of the expert, a declaration stating his or her past or present relationship with the parties, advisors and the tribunal, a statement of qualifications, experience, education and background. It is very important for the tribunal to have a clear understanding with regard to the qualifications of the expert who would affect the tribunal's impression of the expert.

One of the most important characteristics that an expert should have is credibility. This is primarily created through the expert's experience and qualifications. Such information is usually exhibited to the expert report as the expert's curriculum vitae. Another significant aspect of an expert opinion is independence and objectivity. As stated in the above-paragraph, an expert will disclose his or her present and past relationship with the people involved in the proceedings, namely, the parties, tribunal, and advisors, in addition to providing a statement of independence.

An expert's credibility is directly related to his or her independence. This could not be solely achieved through the disclosures or the statement of independence. It is crucial that the opinion given by the expert with its reasoning clearly portrays such objectivity.

Besides having an impressive resume, the content of the expert report will have the biggest impact on the tribunal. The two important elements of credibility and independence must be evidenced by the report. This will be achieved through the reasoning of the opinion, the supporting documents that are submitted, language and methodology.

The IBA Rules under Art. 5 (d) and (e) also provide that the report should include facts that it is based on, opinions and conclusions, including methods as well as evidence and information that is used to shape the opinion. It is important that the expert does not act as the arbitrator and give an opinion as to how the case should be resolved; his or her task should be to address the questions of the parties in an impartial manner.

Experts Appointed by the Tribunal

In cases where a tribunal deems it necessary to lean on the knowledge of a specific issue over which it has no particular specialty, it may choose to appoint an expert. Art. 26 of the UNCITRAL Model Law on International Commercial Arbitrations ("Model Law") provides that a tribunal may appoint an expert in relation to specific issues it needs to determine. It is within the tribunal's discretion to consult the parties when selecting experts, or deciding upon the scope of an experts' opinion. The tribunal may also request the expert to submit a preliminary report upon which the parties may comment. Such comments should be taken into account by the expert in its final report1.

Under IBA Rules Art. 6, it is provided that a tribunal must consult with the parties in appointing an independent expert. The tribunal will set out the terms of reference for the expert it has appointed after consulting with the parties. The parties may inform the tribunal if they have any objections to the expert after the expert has submitted his or her qualifications and a statement of independence. Thereafter the tribunal will consider any objections. From this point onward, the parties may only object to any qualifications and statements of independence of the expert if the subject of the parties' objection comes to light after the expert's appointment.

IBA Rules Art. (6) (3) further provide that the expert can request the parties to submit documents, goods, samples, etc., that are relevant to the case, and the expert's authority to request such information and documents will be treated the same as the tribunal's.

Counsel's Role and Relation with Experts

The counsel's role with regard to experts is mainly two-fold. The primary duty of the counsel is to appoint the right expert for the case. This determination will be based upon the subject matter of the dispute, facts and circumstances. It is generally accepted that an effective expert has a solid reputation, significant knowledge of the subject matter, as well as being author of publications in that regard, has broad experience in cases of similar subject matters in disputes, is independent, credible, professional, familiar with the cross-examination process, has solid communication skills, and is talented in explaining complex matters in simple and understandable language2.

The second duty of the counsel is to prepare the expert. Following the appointment of the expert, the counsel will inform the expert as to the subject matter, and the issues over which his or her opinion is needed. The problem with this task is the counsel's level of involvement in the process. In practice, due to the fact that the exchange of communication between the counsel and the expert are confidential, there is a risk that the expert report will end up reflecting the counsel's voice, rather than the expert's. There is some criticism that experts are "hired guns." However, many practitioners believe that it is unlikely for the expert to risk his or her reputation and credibility and, therefore, most of the expert reports tend to reflect the experts' impartial opinions, without solely reflecting the counsel's strong views.

It is not hard for an experienced tribunal to understand whether an expert opinion is biased or not, especially when during cross-examination an expert who does not defend his or her own findings and opinions, the expert will portray an unreliable image. It is also suggested that witness conferencing or "hot-tubbing" is helpful to obtain unbiased, reliable information. Experts tend to be more accurate when they are challenged, together with another expert.

Legal Experts

Practitioners and arbitrators have differing opinions when legal experts are in question. In this respect, common and civil law traditions have different understandings. In common law practice, foreign law is considered as a fact that needs to be proved; whereas, in civil law traditions, the court is expected to know the law3. Whether or not a tribunal will consider a legal expert necessary depends on the applicable law in the case. Generally, when applicable law is international law, or usages of trade, lex mercatoria, etc., it is expected for the tribunal to be familiar with the rules. In such cases, a separate legal opinion from a legal expert is not considered necessary. However, in cases where a particular domestic law is applicable, a report from a legal expert can be useful since the dynamics and rules of domestic laws differ one from the other.


A non-biased and independent expert opinion is considered to be a useful tool in international arbitration. Despite debates with regard to its admissibility, most tribunals prefer the parties to appoint experts for matters that require special knowledge.


1 Starrett Housing Corp v The Government of the Islamic Republic of Iran (1987) 16 Iran-US CTR 1112, p. 117-118, par. 6.155.

2 Pierre Bienvenu and Martin Valasek, "Witness statements and experts reports," in R. Doak Bishop and Edward G. Kehoe, The Art of Advocacy in International Arbitration, Second Edition, Juris (2010), Chapter 10, p. 263 seq.

3 Bernard Hanotiau, "Civil Law and Common Law Procedural Traditions in International Arbitration: Who Has Crossed the Bridge?" in Arbitral Procedure at the Dawn of the New Millenium: Reports of the International Colloquium of CEPANI, October 15, 2004, p.96.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on

Click to Login as an existing user or Register so you can print this article.

Some comments from our readers…
“The articles are extremely timely and highly applicable”
“I often find critical information not available elsewhere”
“As in-house counsel, Mondaq’s service is of great value”

Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:
  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.
  • Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.
    If you do not want us to provide your name and email address you may opt out by clicking here
    If you do not wish to receive any future announcements of products and services offered by Mondaq you may opt out by clicking here

    Terms & Conditions and Privacy Statement (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

    Use of

    You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these terms & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.


    Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of information available from this server.

    The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.


    Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

    • To allow you to personalize the Mondaq websites you are visiting.
    • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
    • To produce demographic feedback for our information providers who provide information free for your use.

    Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

    Information Collection and Use

    We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

    We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to with “no disclosure” in the subject heading

    Mondaq News Alerts

    In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.


    A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

    Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

    Log Files

    We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.


    This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

    Surveys & Contests

    From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.


    If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.


    From time to time Mondaq may send you emails promoting Mondaq services including new services. You may opt out of receiving such emails by clicking below.

    *** If you do not wish to receive any future announcements of services offered by Mondaq you may opt out by clicking here .


    This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to

    Correcting/Updating Personal Information

    If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to

    Notification of Changes

    If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

    How to contact Mondaq

    You can contact us with comments or queries at

    If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at and we will use commercially reasonable efforts to determine and correct the problem promptly.

    By clicking Register you state you have read and agree to our Terms and Conditions