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Expert evidence in International Arbitration: Selecting and appointing experts

28 November 2022

Expert evidence plays a central role in international arbitration and can often 'make or break' a case. In the first of two articles on expert evidence in international arbitration, Katherine Doran and Iona Hamilton discuss practical advice for the selection and appointment of experts, and relevant procedural rules.

Practical Considerations

It is important that particular care is taken when selecting and instructing an expert witness, as there are a number of practical considerations which will need to be taken into account. It is essential that this process is managed by legal representatives to ensure that the role of the expert and their duties is clearly set out.


It will often be helpful to involve experts early, even before a dispute has formally crystallised or proceedings are afoot. This way, advice can be sought on the technical merits of a case as early as possible. However, it is important to properly frame an expert’s remit - someone who investigates a claim, or helps to advance a party’s contention, may later be compromised from providing independent testimony to a tribunal.

If expert evidence is required on a particularly specialist subject, the search for a suitable expert should be conducted as soon as possible, as it may take some time to find someone with the relevant expertise who is not already conflicted.


Parties will need to ensure that expert witnesses are not conflicted.  This is generally addressed prior to an expert's appointment, through thorough conflict checking.  However, problems can and do arise.

Recent years have seen an increase in mergers of professional services firms, and firms operating and marketing globally under a common brand.  This can present conflicts of interest, as was the case in Secretariat Consulting PTE Ltd & Others v A Company (2021).  In this case, a conflict was found to exist between different entities within the Secretariat International group, such that the UK branch was injuncted from acting as an expert witness. The Court of Appeal held that the duty to avoid conflicts of interest was owed to the client by the entire group – even though the client in question had only ever retained experts from a single branch.

"Soft conflicts", or perceived conflicts can also be problematic, where instructing parties feel an unease about a particular expert and their previous involvement with the arbitrators or other parties in the arbitration.  While there may not legally be a conflict, it can nevertheless be a barrier to instruction.

Suitability, Expertise and Credibility

Clearly expert witnesses must possess the requisite expertise and qualifications.  However, they must also be able to communicate their evidence in a clear and effective manner. It is important that experts are able to give explanations in a very clear and digestible way so they can be understood by laypeople – in particular, a tribunal who may not possess the same expertise as the witness.

Instructing parties should also consider whether theoretical expertise is sufficient.  In many cases it will be beneficial to use an expert who has practical experience of the issues at hand.  For example, a very eminent expert's evidence may be undermined if it emerges that they have not practiced in the field for many years.


When an expert is first instructed, parties may not yet know if a case will run, much less to what timetable.  This can make it difficult to assess experts' availability – particularly in the case of experts who are particularly busy and much in demand.  It will be necessary to ensure that any expert who is instructed has sufficient time to dedicate to the case, particularly at the anticipated pinch points in the process.

Parties and proposed experts need to be conscious that construction and infrastructure disputes may take years to finally resolve.  For example, an expert may be instructed shortly after an incident on a project.  However, it could take a number of years until the case ultimately proceeds to a final hearing. During that time the expert may retire or his or her health may deteriorate, making their continued involvement in the dispute challenging. In such circumstances, parties will need to consider their back up plans, such as support for the expert, or instructing additional experts – both of which will almost certainly have cost implications, and may delay proceedings while a new expert gets up to speed on the factual evidence.

Procedural Rules

There are also various procedural rules which will dictate how expert evidence may be used, and tribunals will often have wide discretion in how they manage expert evidence.

This is one of the areas where we see a different approach between common and civil law traditions. In common law jurisdictions, party appointed experts are the norm; whereas in civil law jurisdictions, it is more common to have experts appointed by the tribunal. In international arbitration, party appointed experts are more widely used, though many of the rules regarding expert evidence apply specifically to tribunal appointed experts. 

Relevant Law

The seat of arbitration will be crucial in determining which laws apply to the use of expert evidence.

For example, for arbitrations seated in England, the Arbitration Act 1996 contains rules regarding the use of evidence. Section 33 provides that the tribunal has a general duty to give parties a reasonable opportunity to present their case. The Act goes on to state that the tribunal may appoint experts to report to it and the parties “unless otherwise agreed by the parties” (section 37).

This can be contrasted with the French arbitration rules which provide that the tribunal has total freedom to make decisions regarding expert evidence, including appointment of experts. A middle ground is found in the Swedish Arbitration Act which permits the tribunal to appoint experts unless both parties are opposed (section 25).

Procedural Rules

The procedural rules governing the arbitration will also dictate how expert evidence can be used. For example, Article 25 of the ICC Rules stipulate that the tribunal shall establish the facts of the case.  The tribunal may decide to hear experts appointed by the parties, or it may, after consulting with the parties, appoint its own experts.

The LCIA Rules are far more extensive. Article 20 sets out rules for the naming of experts and the exchange of reports, as well as the tribunal's power to allow, refuse or limit written and oral testimony.  Under the LCIA Rules, the tribunal also has powers to appoint their own expert and to request witnesses to attend for oral questioning (Articles 20 and 21).

Soft Law Sources

In addition to the procedural rules in the arbitration agreement, there are also various soft law sources which can support the appointment of expert witnesses. A good example of this is the IBA Rules, Article 5 of which goes into some detail regarding the use of party appointed experts and the requirements for their reports.

Another example is the CIArb Protocol for the Use of Party Appointed Expert Witnesses in International Arbitration. The Protocol expands on the IBA Rules and gives details about tests and analyses which may need to be conducted and provides further guidance regarding the contents of expert reports, independence of experts and privilege. Both the IBA Rules and the CIArb Protocol can be adopted into an arbitration procedure in their entirety.


It is essential that care is taken in selecting a suitable expert, and appointing them to give evidence. DWF regularly instructs expert witnesses, and can guide you through the process, to ensure you instruct a suitably qualified expert, and that their appointment is managed in a way which complies with the relevant laws and procedural rules.

Authors: Katherine Doran and Iona Hamilton

Further Reading