Party-Appointed Experts in International Arbitration: Grounds for Involvement and the Essence of Duties

The involvement of experts is a common practice due to the complexity of cases being considered in international arbitration. For instance, the arbitrator or parties’ legal counsel may be limited in comprehending the foreign law which should be applied in that particular dispute. A similar lack of knowledge may relate to complex technical or quantum issues. In these circumstances legal, technical, or quantum experts will be important participants of arbitration, who are meant to assist the tribunal with their professional views on various matters for attaining the aims of arbitration.

There is a common view about the division of experts into party-appointed experts and tribunal-appointed experts in both the theory and practice of international arbitration. Taking into consideration existing concerns about possible risks of involvement of party-appointed experts into arbitration related to marking them as advocates or “hired guns”, it may be useful to describe in a general way the main aspects related to the involvement of such figures in international arbitration with making emphasis on their duties.

The example of definition of party-appointed expert is proposed in the IBA Rules on the Taking of Evidence in International Arbitration (2020) (hereinafter – the IBA Rules), where it is meant as a person or organization appointed by a party in order to report on specific issues determined by the Party.

The question as to whether it is necessary in principle to involve experts into the proceedings by the parties may be explained through the example of law experts as widely used kind of party-appointed experts. According to the Chartered Institute of Arbitrators Guideline on Party-Appointed and Tribunal Appointed Expert Witnesses (hereinafter – the CIArb Guideline on Expert Witnesses) the following factors need to be taken into account when considering the benefit of adducing expert opinion on the law: (1) the degree of familiarity of arbitrators with the applicable law and/or similar system(s) of law; (2) the degree of counsel’s competence in and familiarity with the applicable law and/or similar system(s) of law; (3) the extent to which the application of the law will impact on that issue and the likely effect this will have on the case; and (4) whether it involves general legal principles or some unique aspects of the applicable law.

The International Chamber of Commerce (ICC) Techniques for Controlling Time and Costs in Arbitration (2018) specify other preliminary issues which may be important for parties aiming to attain efficient and cost-effective arbitration procedures. As for clarity regarding the subject matter and scope of expert reports, it is essential for there to be clarity at an early stage (by agreement, if possible) over the subject matter and scope of any expert evidence to be produced. This will help to ensure that the experts appointed by the parties have similar expertise and address the same issues. Another issue relates to the number of experts. Other than in exceptional circumstances, there should be no need to be more than one expert per party for any particular area of expertise.

When taking into consideration the possible ways of involving party-appointed experts into arbitration, two options are mentioned in the CIArb Guideline on Expert Witnesses. The first way means that each party appoints their own experts, whereas the second is the joint agreement of the parties to appoint a single expert. The appointment of the expert by each party is the most frequently used in practice as the right of the parties to appoint an expert witness is an integral part of their right to submit evidence and to be heard. Although the appointment of a single joint expert is considered as being rare practice it may be used by the parties to reduce their costs.

Revealing the duties of party-appointed experts requires consideration of provisions included in different sources. One of the most helpful documents is the Chartered Institute of Arbitrators Protocol for the Use Party-appointed Expert Witnesses in International Arbitration (2007) (hereinafter – the CIArb Protocol) which outlines in detail a regime designed to govern the use of party-appointed experts in international arbitration in an efficient and economic manner.

As one of the principles for the preparation and giving of expert evidence under the CIArb Protocol it is stated that experts should provide assistance to the Arbitral Tribunal and not advocate the position of the Party appointing them. The role of the expert as the figure effectively assisting the tribunal is confirmed through the establishment of the duty of the expert to assist the Arbitral Tribunal to decide the issue or issues in respect of which expert evidence is adduced in Article 4.3 of the CIArb Protocol. This duty is also highlighted in the expert’s declaration referred to in Article 4.4(k) of the CIArb Protocol which shall include the following statement: “I understand that my duty in giving evidence in this arbitration is to assist the arbitral tribunal to decide the issue or issues in respect of which expert evidence is adduced. I have complied with, and will continue to comply with, that duty…”.

The importance of the understanding the role of expert through the duty of assistance is reiterated also in the Society of Construction Law (Singapore) Protocol for the Use of Experts’ Joint Statements in Arbitration (2026) (hereinafter – the SCL (S) Protocol) by stating that the basic function of expert evidence is to assist the Tribunal or Court in making a decision on the key issues in dispute.

Another notable explanation of the duty of the expert may be found in the foreign statutory instrument – Civil Procedure Rules (1998) (hereinafter – the CPR) which governs the rules of civil procedure in England and Wales. Rule 35.3 of the CPR establishes the overriding duty of experts to the court. Under this rule it is the duty of experts to help the court on matters within their expertise. It is also stated that this duty overrides any obligation to the person from whom experts have received instructions or by whom they are paid.

It seems reasonable to assume that other duties of party-appointed experts in international arbitration which may also be qualified as requirements or standards are inextricably connected with the duty of the expert described above. Regardless of the fact that not much attention is given to the status of party-appointed experts in arbitration rules of arbitration institutions, there are still appropriate directions which are given in other sources of regulation.

Under the Rules of Transnational Civil Procedure (2005) which are appended to the ALI/UNIDROIT Principles of Transnational Civil Procedure (2004), a party-appointed expert is governed by the same standards of objectivity and neutrality as a court-appointed expert. The IBA Rules define a statement of an expert’s independence from the Parties, their legal advisors and the Arbitral Tribunal as among the essential elements of the expert report submitted by a party-appointed expert (Article 5(2) (с) of the IBA Rules). Pursuant to Article 4 of the CIArb Protocol, an expert’s opinion shall be impartial and objective. It also provides that payment by the appointing Party of the expert’s reasonable professional fees for work carried out in giving such evidence shall not, of itself, impair the expert’s impartiality.

The interrelationship between an expert’s duty to assist the court and the requirements of objectivity and independence may be well illustrated by reference to Practice Direction 35 – «Experts and Assessors» which supplements Part 35 of the CPR and establishes the following general requirements for expert evidence. Expert evidence should be the independent product of the expert and uninfluenced by the pressures of litigation. Experts should assist the court by providing objective, unbiased opinions on matters within their expertise, and should not assume the role of an advocate. Experts should consider all material facts, including those which might detract from their opinions. Experts should make it clear – (a) when a question or issue falls outside their expertise; and (b) when they are not able to reach a definite opinion, for example, because they have insufficient information. If, after producing a report, an expert’s view changes on any material matter, such change of view should be communicated to all the parties without any delay and, when appropriate, to the court.

Disclosure obligations may be considered as being an important means of ensuring an expert’s independence. According to Article 5(2) (a) of the IBA Rules the expert report shall contain a statement regarding a party-appointed expert’s present and past relationship (if any) with any of the Parties, their legal advisors and the Arbitral Tribunal. Similar requirement is established for an expert’s written opinion in Article 4.4 (b) of the CIArb Protocol. The expert written opinion should state any past or present relationship with any of the Parties, the Arbitral Tribunal, counsel or other representatives of the Parties, other witnesses and any other person or entity involved in the said Arbitration.

Careful attention on the part of the parties in selecting the expert based on their thorough and honest understanding of the duties of the expert, should be crucial in light of possible negative consequences of violation of duties by the expert. For example, under Rule 29.4 of the Rules of Transnational Civil Procedure the court and the parties may challenge a witness’s credibility or the authenticity or accuracy of documentary evidence. It is explained that the credibility of any witness, including experts and parties, can be disputed on any relevant basis, including questioning, prior inconsistent statements, or any other circumstance that may affect the credibility of the witness, such as interest, personal connections, employment or other relationships, incapacity to perceive and recollect facts, and inherent implausibility of the testimony. Prior inconsistent statements may have been made in earlier stages of the same proceedings (for instance, during deposition) or made out of the judicial context like, for instance, before the start of the litigation.

Party-appointed experts continue to play an important role in international arbitration. It is obvious that the mere way of appointment of these experts as well as receipt of remuneration from the parties raises reasonable doubts regarding the possibility of party-appointed experts acting independently before the tribunal. Another peculiarity in the status of such experts is the insufficiency of its regulation by arbitration rules of arbitration institutions, which deepens any existing doubts. However, addressing both different soft instruments of regulation in arbitration and some significant examples of national legislation governing civil process, demonstrates clearly that the potential risks of involvement of the expert by the parties may be effectively minimized not least due to the understanding of the core of the main expert’s duty before the tribunal and the related duties of objectivity and independence not only by the parties but by the expert himself.