Use and misuse of expert evidence

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Use of experts in common law jurisdictions

Kenneth Juan Figueroa
Foley Hoag, Washington, DC


The role of the party-appointed expert under the common law approach

In common law jurisdictions, the fundamental purpose of experts and expert witnesses is to assist the client or the trier of fact (be it a judge, jury or arbitrator) to understand the technical issues at hand. To qualify as an expert, one must possess sufficient knowledge and expertise, gained either by formal study or by experience in a specialised field.

There are, in effect, two principal roles for experts. First, there is the advisory expert who is retained by the client or client’s counsel to assist in understanding technical aspects of the client’s case and, in this sense, plays an important role building or better substantiating a client’s affirmative case or defence. There are no formal rules with respect to advisory experts and the client and client’s counsel must rely on their own due diligence in vetting appropriate experts for each case. Second, there is the testifying expert who presents their expert opinion to the trier of fact. Testifying experts are subject to express requirements concerning their qualifications. In the United Kingdom, this requirement is set out in the Civil Procedure Rules (CPR), Practice Direction (PD) 35;1 and in the United States, under the Federal Rules of Evidence (FRE), 702.2

In addition, both jurisdictions have guiding principles for admissibility of evidence. In the US, under FRE 703, experts may rely on data published by others. Three key cases, known as the Daubert trilogy,3 define criteria that may be applied to determine whether investigations undertaken by the expert can be relied upon: (1) whether the theory or method can be empirically tested; (2) whether the technique has been subjected to peer review or publication; (3) whether potential error rates can be controlled; and (4) whether the proposed methods are generally accepted within the specific community. Under the UK jurisdiction, there is no formal test for determining the admissibility of expert evidence, but various consultation papers have set guidelines to ensure the reliability of expert testimony, at least in criminal proceedings.4

The laws regarding the role of expert witnesses under the UK and US jurisdictions are considerably different in three notable ways: degree of impartiality of expert witnesses, use of depositions and expert witnesses’ ability to opine on the ‘ultimate issues’. Under the UK jurisdiction, more measures are in place to remind experts that their primary mandate is ‘to serve the Courts and not their fee payers’. In general, US courts appear to be more relaxed in relation to the conduct of experts.

Independence and impartiality of the expert witness

Rules governing the conduct of experts seem to be better developed in the UK than the US and have increased over the years. In the UK, for example, in cases such as ‘The Ikarian Reefer’5 and Davies v Magistrates of Edinburgh,6 the duties of the expert are set out clearly. Not only does the appointed expert have an overriding duty to the court, but they must remain independent and impartial and identify in their testimony any opinions held that do not support the case put forward by the party who appointed them. In addition, under the CPR PD 35.10(2), at the end of an expert’s report, they must include a statement that they are aware of their duties and have fulfilled them, and will continue to do so.

By comparison, the law in the US is often perceived to be less prescriptive. The FRE neither formally defines the duties of an expert witness nor contains any specific written obligation for the expert to be independent. As one expert consultancy has pointed out: ‘This distinction between the UK and US jurisdiction has prompted views of greater expert partisanship in the US.’7

Given the different perspectives concerning experts in the UK and US, one observes a greater incidence of experts ‘double hatting’ in US jurisdictions – that is, the advisory experts directly involved in the independent analysis of the project often also serve as the testifying expert. This is usually frowned upon in the UK, where one sees a clearer distinction between the two expert roles.


Under the US Federal Rules of Civil Procedure (FRCP), Rule 29, any party may take the testimony of any person by the form of oral8 or written9 deposition unless the court orders otherwise. If the deponent fails to attend, they could be compelled to do so by subpoena.10 This rule applies to both fact and expert witnesses. The use of a deposition is considered an important component of discovery in the US legal system, as it enables lawyers to determine the strength of the other side’s evidence, which may lead to early settlement or determine trial tactics.

In comparison, the use of depositions in civil proceedings is uncommon in the courts of the UK (although possible under certain circumstances). Unlike the US system, any cross-examination of an expert must be conducted under oath (or affirmation) in front of a judge. The expert must attend at the agreed trial date, preferably voluntarily but under subpoena, if necessary. Any ambiguity or obfuscation within the expert’s report will be highlighted by the legal counsel (barrister) during cross-examination and may prompt the judge to place less weight on that evidence.11

Ultimate issues

The US and UK jurisdictions have adopted different approaches on whether the expert can opine on issues that the judge (or jury or arbitrator) is ultimately required to decide. In the US, FRE 704(a) permits the expert to opine on the ‘ultimate issue’, as it explicitly states that ‘an expert’s testimony is not objectionable just because it embraces an ultimate issue’.

In contrast, experts under the UK jurisdiction are strictly forbidden from opining on the ultimate issue. Experts must follow the code of conduct and not stray from the instructions given by their lawyers. In the event of digression, the expert could face possible costs sanctions.12 In the words of Lord Cooper, a former head of the judiciary in Scotland: ‘Expert witnesses, however skilled or eminent, can give no more than evidence. They cannot usurp the functions of the jury or the Judge sitting as a jury.’13

The table below summarises key similarities and differences in the use of experts under UK and US law. The comparison pertains to court proceedings, ‘but similar arrangements apply to expert evidence in Arbitration proceedings (although there is sometimes a greater flexibility of procedure in arbitration than in court)’.14


The similarities and differences between approaches of expert use in the UK and US15






Purpose behind the use of expert witnesses

Expert evidence is to furnish the judge or jury with necessary scientific criteria for testing the accuracy of their conclusions.

Expert evidence is admissible on the basis that the knowledge will help the trier of fact to understand the evidence or to determine a fact at issue.


Qualification of expert witnesses

Expert witness is qualified to give evidence, where the court itself cannot form an opinion and special study, skill or experience is required for the purpose.16

An expert witness is qualified by knowledge, skill, experience or education.17


Admissibility of evidence

Expert evidence must be provided in as much detail as possible in order to convince the judge that the expert’s opinions are well founded.18

Expert testimony to be based on sufficient facts, data or products of a credible source of test and tried principles and methods.19


Conduct of expert witness

Expert’s ‘duties to the Court override any obligation to the person from whom they have received instructions or have been paid by’.20

Expert’s duty is not formally defined under the FRCP/Evidence.



Expert evidence is examined before the judge (or arbitrator).

Expert evidence can be compelled to deposition.


Ultimate issues

Expert opinion on the ultimate issue is not admissible.

Expert opinion on the ultimate issue is admissible.


The adversarial nature of the common law approach

The principal difference between the common law approach and the civil law approach to experts is the adversarial nature of common law dispute resolution. The expectation and practice (indeed, the due process rights of the parties) in common law jurisdictions is that each party is entitled to choose its own experts. Court-appointed or tribunal-appointed experts are not the norm and are considered appropriate only in extreme cases.

There are certain advantages to party-appointed experts. The common law approach, of course, envisages party-appointed experts as consistent with the due process right of each party of presenting their case – a notion inconsistent with an inquisitorial tribunal or court. However, beyond that, party-appointed experts have certain practical advantages as well. First, parties know their case and defences much better than the court and, at the outset, will be better immersed in the facts of the case. Parties know where the problems lie, especially with respect to the particular technology or other specialised field that makes the appointment of an expert desirable. As such, they will be better placed to select the experts with the appropriate expertise. Second, competing experts, who will be open to cross-examination, help to provide the court or tribunal with different sets of view that may better enable it to make its own determination. Relying on a single expert risks that the expert may not be the most appropriate for the case or may have flawed premises in their analysis, which may not be adequately tested during a proceeding.

Party-appointed experts also have certain disadvantages. As FTI Consulting has pointed out, the common law approach gives the ‘parties the opportunity to appoint not the more experienced expert in their field of practice but an expert who may be willing to best support the party’s view. Since experts are appointed and paid on the basis of a contractual relationship, some unfortunately may adopt the position of a “Hired Gun,” advocating on behalf of the party which appointed them in an attempt to advance that party’s contentions’.21 As we have seen, the UK in particular attempts to mitigate against this risk by imposing explicit standards of objectivity and impartiality on experts. The US, while less stringent, has more informal pressures borne out during depositions and cross-examination where evidence of an expert’s partiality or ‘hired gun’ status is often quickly brought to light. Related to this disadvantage is that because nearly all areas of technical or legal expertise are subject to interpretation, it is not unusual to have experts present well-founded analyses that result in completely disparate world views and conclusions. The resulting conundrum requires the court or tribunal to make its own determinations or find other ways to reach a middle ground. These include the use of a court-appointed expert and hot-tubbing.

Court-appointed experts in common law jurisdictions22

In the UK, Civil Procedure Rule 35.7 provides the court authority to direct that evidence be given by a single joint expert. Similarly, in the US, FRE 706 (‘Rule 706’) permits a court, on a party’s motion or on its own, to appoint an expert witness to make findings and testify at trial on certain issues.

The use of a court-appointed expert brings its own host of issues, beginning with the selection of an expert. The UK’s CPR Rule 35.7 in the first instance requires that the parties agree on the joint expert, something that may be difficult to do. If the parties cannot agree, the court may select an expert from a list of candidates identified by the parties or in any other manner the court directs. In US federal court, while Rule 706 allows a court to appoint an expert ‘of its own choosing’, in practice, a court will often solicit nominations for a Rule 706 expert from the parties.23 In the Tessera case, for example, each side nominated several candidates, which included university professors who taught or performed research in the technology at issue and people with experience in the relevant industry. Each candidate was then interviewed collectively by the parties. Each side then nominated a proposed candidate for selection by the court.

After the court selects an expert, the court and the parties must address a host of issues related to working with the expert, including what duties to assign to the expert; what materials to provide to the expert to review; how to communicate with the expert; how to adjust the case schedule to permit time for the expert’s report and deposition; how to ensure that the expert understands the intricacies of law and procedure; how to prepare the expert to testify at deposition and at trial; what to tell the jury about the expert’s neutrality; and even how to fairly split the expert’s bill.24

A key question in designing these procedures is how to replace all of the instructions and help that a party expert typically gets from the respective party counsel. Who will help the independent court-appointed expert understand the legal standards for anticipation or prepare claim charts? Who prepares and defends the court-appointed expert at deposition or at trial?25

One possibility is for the parties to engage a third-party attorney as the expert’s counsel. But this adds another layer of expense and complication to the case. Another possibility is using a combination of court orders, scheduling and advice by counsel for the parties. The Tessera case provides a good example of this approach. Following the expert’s appointment in Tessera, the court issued a detailed written order pursuant to Rule 706(b) informing the expert of his duties. Those duties included preparing a written report on claim construction, preparing a written report on patent infringement and validity issues and testifying at trial.26 Timing is also important. In Tessera, the Rule 706 expert’s report was due after the party experts’ reports. This timing allowed the neutral expert to consider and respond to the parties’ experts and may have assisted the Rule 706 expert by providing examples of the detail and structure of expert reports.27 Another issue that has to be dealt with is whether the court-appointed expert will testify and, if so, how that testimony and cross-examination will be structured. There are several possibilities, each of which raises important questions regarding the expert’s preparation and the effect the testimony will have:

• The expert could provide narrative testimony without assistance from counsel. This approach gives the expert freedom to present their views independently, but may lack sufficient clarity and structure if the expert is not an experienced presenter.

• Alternatively, the expert could be examined by counsel for the party that their opinion supports. This approach can add clarity and structure, but the fact-finder might unfortunately perceive the expert as aligned with the examining party.

• The expert could testify before the parties’ experts. This approach can ensure that the fact-finder’s first impressions come from an unbiased source, but may leave the expert without an opportunity to respond fully to the parties’ experts.

• Alternatively, the expert can testify after the parties’ experts. This approach ensures that the expert can fully respond, but might raise a concern that the fact-finder will perceive that as the ‘final word’ on an issue.

It has been commented that ‘[a] court-appointed expert carries a neutral status, unaligned with the litigants’.28 Such expert testimony can be highly persuasive to the jury or trier of fact and the opinions expressed in the expert’s report tend to be extremely influential and outcome determinative. Indeed, this influence led to legal challenges to Rule 706 court-appointed experts in the US, in which parties have argued that the practice impinges on the constitutional right to a jury trial.29 While the US Supreme Court has never ruled on the issues, in 2009, the US Court of Appeals for the Federal Circuit rejected this argument and recognised the constitutionality of Rule 706.30 The court found that compliance with Rule 706 and cautionary jury instructions prevented any encumbrance of the plaintiff’s due process rights.31

Nevertheless, given the concerns and complications that arise with court-appointed experts, in the US at least, courts have noted that their use should be reserved for exceptional cases in which ‘the ordinary adversary process does not suffice’.32 Court-appointed experts are very rarely used and are most commonly used in ‘unusually complex’ cases with ‘starkly conflicting expert testimony’.33 In appointing an independent expert in the Tessera case,34 the court commented that ‘the complexity of the technology at issue in this case will be particularly difficult and confusing for the jury to understand’.35 The court also pointed to ‘stark conflicts’ in the parties’ positions.

The Federal Judicial Center conducted a small-scale empirical study on this topic and summarised its findings as follows:

‘In brief, we found that much of the uneasiness with court-appointed experts arises from the difficulty in accommodating such experts in a court system that values, and generally anticipates, adversarial presentation of evidence’.

The Federal Judicial Center also made the following specific findings:

• ‘Judges view the appointment of an expert as an extraordinary activity that is appropriate only in rare instances in which the traditional adversarial process has failed to permit an informed assessment of the facts. We found no evidence of general disenchantment with the adversarial process by judges who had made such appointments.

• Parties rarely suggest appointing an expert and typically do not participate in the nomination of appointed experts.

• The opportunity to appoint an expert is often hindered by failure to recognise the need for such assistance until the eve of trial.

• Compensation of an expert often obstructs an appointment, especially when one of the parties is indigent.

• Judges report little difficulty in identifying persons to serve as court-appointed experts, largely because of the judges’ willingness to use personal and professional relationships to aid the recruitment process.

• Ex parte communication between judges and appointed experts occurs frequently, usually with the consent of the parties.

• The testimony or report presented by an appointed expert exerts a strong influence on the outcome of litigation.’36

In conclusion, while courts and tribunals have the option of appointing experts, their use raises certain issues that make it an imperfect solution to the problem of disparate party-appointed experts.

Beyond court-appointed experts, certain common law jurisdictions, such as Australia and the UK, expressly permit courts to order concurrent expert testimony, otherwise known as ‘hot-tubbing’. In the US, courts also occasionally use concurrent testimony. This method is commonly used in international arbitration as well. While some judges and arbitrators have claimed that this procedure can be useful, counsel are often reticent in permitting hot-tubbing, given the lack of control that it implies. Its effectiveness can also be undermined where experts are unwilling to modify their positions or where the relationship between experts is such that it unfairly favours one expert over another. An example is a case where one expert is the former professor of the second expert.

Hot-tubbing and other innovative solutions are discussed in further detail in a separate article. However, it bears keeping in mind that the innovative use of experts is largely a result of courts and tribunals attempting to reach a middle ground where two party-appointed experts have provided extreme or diametrically opposed conclusions. None of these innovative solutions, however, is perfect and they raise issues that may undermine their effectiveness and, in extreme cases, perhaps even undermine the parties’ rights.


The common law approach places a high value on the adversarial nature of dispute resolution. In this context, the use of party-appointed experts is a cornerstone of the parties’ rights and strategy. However, misapprehension concerning the integrity and independence of experts under this approach has been frequently raised. For instance, in Finkelstein v Liberty Digital Inc,37 the judge highlighted that ‘[t]hese starkly contrasting presentations have, given the duties required of this court, imposed upon trial judges the responsibility to forge a responsible valuation from what is often ridiculously biased “expert” input.’

Scholars have observed that the ‘chief unsustainable myth is the complete independence of the expert’.38 The role of expert witnesses in common-law jurisdictions has been described as ‘ambiguous’39 and involving ‘unresolved contradictions’.40

These concerns are unavoidable. Notwithstanding formal and informal requirements of impartiality and objectivity of experts, the fact of the matter is that because they are party-selected, they will have been chosen for espousing a certain world view or approach to their area of expertise that most closely aligns with the parties’ case. As such, no matter how objective an expert is, the expert’s opinion will always be partial. In the author’s view, this should be accepted and embraced. Accordingly, parties’ counsel should be prepared to test the expert’s analysis for flaws and conscious or unconscious bias. The judge, jury or arbitrator must be ready to take the expert’s opinion with a large grain of salt and also be ready to test the expert, perhaps through methods such as hot-tubbing or other approaches. In the author’s view, this testing of experts has greater advantages then relying on a single court or tribunal appointed expert.



1 See https://www.justice.gov.uk/courts/procedure-rules/civil/rules/part35/pd_part35 accessed 26 February 2019.

2 See www.law.cornell.edu/rules/fre accessed 5 November 2018.

3 Daubert Trilogy: Daubert v Merrell Dow Pharmaceuticals, Inc, US 579 (1993), General Electric Co v Joiner, 522 US 136 (1997) and Kumho Tire v Carmichael, 526 US 137 (1999).

4 Eg, in 2009, the Law Commission published a consultation paper titled ‘The Admissibility of Expert Evidence in Criminal Proceedings’, and in January 2013, the UK Ministry of Justice published ‘Report on the Implementation of Law Commission Proposals’. See FTI Consulting Report, p 2.

5 Ikarian Reefer 1993 2 LILR 68, 81–82. Cited in the FTI Consulting Report, p 2.

6 Davies v Magistrates of Edinburgh 1953 SC 34, SLJ 54. Cited in the FTI Consulting Report, p2.

7 FTI Consulting Report, p 2.

8 FRCP, r 30.

9 FRCP, r 31.

10 FRCP, r 45(B).

11 FTI Consulting Report, p 3.

12 Philips and Others v Symes and Others 2 [2004] EWC 2330 (Ch), [2005] 4 ER 519. Cited in FTI Consulting Report, p 3.

13 Ibid, 14, p 40. Cited in FTI Consulting Report, p 3.

14 FTI Consulting, ‘The Evolution of Expert Witness Law Under UK and US Jurisdiction’ www.fticonsulting-asia.com/~/media/Files/apac-files/insights/white-papers/the-evolution-of-expert-witness-law-under-uk-and-us-jurisdiction.pdf accessed 5 November 2018.

15 Ibid.

16 Lord Mansfield, Folkes v Chadd (1782) 3 Doug 157.

17 FRE 702.

18 UK Register of Expert Witnesses, Factsheet 02: Expert Evidence www.jspubs.com/experts/fs/02.pdf accessed 5 November 2018.

19 FRE 702 (b–d).

20 Civil Procedural Rules 35.3(2).

21 FTI Consulting Report, p 2 www.fticonsulting-asia.com/~/media/Files/apac-files/insights/white-papers/the-evolution-of-expert-witness-law-under-uk-and-us-jurisdiction.pdf accessed 5 November 2018.

22 The following article was very helpful on this topic. Philip Woo, ‘Court-Appointed Experts – A Powerful but Rarely Used Tool’, (‘Sidley Report on Court-Appointed Experts’) (2015) www.law360.com/articles/652686/court-appointed-experts-a-powerful-but-rarely-used-tool accessed 5 November 2018.

23 While Rule 706 allows for a court-appointed expert, it provides little guidance on when to use such an expert, how to select one or to how to work with the expert during litigation and at trial. Sidley Report on Court-Appointed Experts.

24 Sidley Report on Court-Appointed Experts.

25 Ibid.

26 Ibid.

27 Ibid.

28 Ibid.

29 See Monolithic Power Systems, Inc v O2 Micro Intern Ltd, 558 F.3d 1341, 1348 (Fed Cir 2009) (‘Such experts tend to become in the eyes of the jury anointed, not appointed’ – quoting 1973 letter in the Congressional record). In addition, the plaintiff in the Tessera case echoed this concern: ‘If the Court has something more than [the expert providing a neutral technology tutorial to the jury] in mind, such as the possibility of an expert providing testimony on substantive legal issues in the case, Tessera’s concerns about potential bias would increase considerably.’ Tessera, Inc v Adv Micro Devices, Inc et al, No 4:05-cv-4063 Plaintiff Tessera, Inc’s Brief Re Case Management Schedule and Appointment of Court Expert Order (ND Cal 2 April 2 2007), ECF No 426.

30 See Monolithic Power Systems, 558 F3d 1341, 1348.

31 See n 24 above.

32 In re Joint E & S Dists Asbestos Litig., 830 F Supp 686, 693 (EDNY 1993).

33 Oracle America, Inc v Google Inc, 2011 US Dist Lexis 129766 (ND Cal 9 November 2011).

34 Tessera, Inc v Adv Micro Devices, Inc et al, No 4:05-cv-4063 Order (ND Cal 26 March 2012), ECF No 984.

35 Ibid.

36 Federal Judicial Center, ‘Court-Appointed Experts: Defining the Role of Experts Appointed Under Federal Rule of Evidence 706’ (1993) www.fjc.gov/sites/default/files/2012/Experts.pdf accessed 5 November 2018 pp 4–5.

37 Harold Finkelstein and Marilyn Finkelstein v Liberty Digital Inc [2005] CA No 19598 (quoted in the FTI Consulting Report www.fticonsulting-asia.com/~/media/Files/apac-files/insights/white-papers/the-evolution-of-expert-witness-law-under-uk-and-us-jurisdiction.pdf accessed 5 November 2018).

38 Bartlett (1994) the Expert ‘independence and parties’ ownership’. Cited in the Nicholas Gould, Fenwick Elliott Report: World Launch: ICC Expert Rules-- A User Perspective: When and How to Involve Experts in International Arbitration Proceedings and other ADR Processes, p 1 (January 2015) available at https://www.fenwickelliott.com/sites/default/files/ng_-_icc_launch_of_expert_rules.pdf.

39 A Shilston (1992) ‘Some reflections on the role of the expert witness’ 58, JCIArb 4-251-258. Cited in the Fenwick Elliott Report, p 1.

40 A Speaight (1996) ‘Expert evidence – seven pillars of wisdom, but are they sound?’ 62, JCIArb 4-269-271. Cited in the Fenwick Elliott Report, p 1.


Kenneth Juan Figueroa is a partner at Foley Hoag, Washington, DC. He can be contacted at kfigueroa@foleyhoag.com. The author would like to thank Jean Lee for valuable research assistance.



The civil law approach – court-appointed experts

Christian Johansen
Bruun & Hjejle, Copenhagen


The general rule: civil law

The general rule on expert witnesses is that experts are court-appointed, and this role of appointment and the function of experts are governed by legislation. By legislation, parties in court (or arbitral) proceedings can request the court or tribunal to appoint one or more experts to give expert statements on specific aspects of the dispute.

In general, the role of a court-appointed expert is to answer specific questions raised by the parties on matters relevant for the court’s decision on technical, financial or technological issues relevant for one or both parties.

As the expert is appointed by the court, the questions to be answered are approved by the court and the expert is appointed by the court to support the court in providing the basis for its legal decision in deciding the dispute.

Background and principles for the general rule

The regime of court-appointed experts is based on the civil law approach such that the national state by legislation provides the framework for the parties to have fair presentation of evidence in civil proceedings, which is partially fulfilled by offering an objective and independent expert.

This means that civil law consists of comprehensive legal codes also governing the use of court-appointed experts and other experts, including party-appointed experts.

The purpose of court-appointed experts is to secure the neutrality and impartiality of the expert. Furthermore, the court’s exclusive power to appoint an expert ensures that the ongoing process to appoint the expert is not delayed by the parties’ inability or unwillingness to agree on an expert.

Court-appointed experts, party-appointed experts and expert witnesses

Court-appointed experts

The use of experts is closely related to the concept of burden of proof. The party with the burden of proof is in need of an expert to explain technical issues and give an opinion to assist the court and will, in the civil law system, generally ask for expertise on specific matters with a request to the court to have a qualified and neutral expert appointed.

Parties usually have the opportunity to propose a specific expert, but the court is not bound by such a proposal. If the parties agree on a specific expert, the court will, however, often appoint that expert.

In some civil law jurisdictions, it is a requirement that the court-appointed expert is chosen from a register containing people with specific professional and technical skills. In Italy, for example, the court-appointed expert (a consulente tecnico d’ufficio or CTU) has to be chosen from the Italian register (Albo dei Periti).

As the expert is appointed by the court, the expert report has high evidentiary value. The courts often base the judgment on the expert’s opinion and most often disregard any conflicting statements from witnesses, parties or party-appointed experts.

Party-appointed experts

The use of party-appointed experts is usual in civil jurisdictions, despite the usual appointment of court-appointed experts.

Party-appointed experts are often used as consultants to support and develop legal positions regarding technical, economical or similar statements in relation to a dispute.

This leads to a conflict in procedural law about whether evidence from party-appointed experts is permissible evidence, including the question of whether statements and conclusions from party-appointed experts can be submitted to a court-appointed expert as basis for their report.

In some jurisdictions, the rule is that statements from a party-appointed expert are only admissible as evidence if the report is obtained before proceedings are initiated. However, this will often lead to an unfair situation because an expert report is not known to the other party until after proceedings are initiated, thus preventing the other party from presenting its own expert.

As a result, new rules were adopted in Denmark in 2016, making it possible for the other party to present reports as a response without regard to the time at which they were obtained.

This means that each party can present its own expert report obtained before legal proceedings and at the same time the opponent has the opportunity to obtain its own report from a party-appointed expert as a response, also after court proceedings have started.

In Italy, the procedure is different. Only after the court appoints an expert are the parties given the opportunity to hire their own expert (a consulente tecnico di parte or CTP). CTPs can make comments on the court-appointed expert’s report, which either supports or criticises the conclusions of the court-appointed expert.

Expert witnesses

In some civil law jurisdictions, it is also possible for parties to present statements from party-appointed experts as a supplement or alternative to court-appointed experts. However, it is required that the parties agree on this. It should be noted that this approach is more commonly used than court-appointed experts in some civil law jurisdictions, such as Sweden.

By this approach, the expert witness is an instrument to avoid court-appointed experts. Because the parties themselves appoint the expert, such a report will, however, have less evidentiary value than that obtained from a court-appointed expert.

Different approaches in civil law in drafting terms of reference for experts

When drafting terms of reference, different approaches are used in civil law jurisdictions.

In Denmark, the general rule is that the parties jointly determine the scope by drafting specific questions to be answered by the expert. Furthermore, the parties can submit whatever questions they find relevant and the parties cannot, as a rule, make objections to the counterparty’s questions. In some civil law jurisdictions, the court has a more active role in drafting questions. In other jurisdictions, the court will assess the questions and answers as part of the normal assessment of evidence.

In Germany, the scope of the statement from the court-appointed expert is determined exclusively by the judge, who also sets out rules for the expert’s communication with the parties. A similar approach applies in Norway. However, the parties have the opportunity to comment on the references and the court has the opportunity to instruct the parties in how to define the questions the expert has to answer.

In Italy, the approach is different. A CTU acts as an assistant to the judge, thus making the judge responsible for determining the scope of the expert’s report.

Party-appointed experts under civil law, inside and outside the court regime

Regardless of the approach when drafting terms of reference, party-appointed experts can affect the court-appointed expert’s report.

If the parties determine the scope of the expert’s report themselves, a party-appointed expert will often be the person who assists in the scoping of questions to the court-appointed expert. The party-appointed expert acts as consultant and will often continue to do so during the entire dispute. Further, the party-appointed expert will influence the court-appointed expert’s report by asking specific questions that work in one party’s favour.

In other civil law jurisdictions, where the court alone determines the scope of the expert, a party-appointed expert can influence the result. This can be done for instance by letting the party-appointed expert (in Norway) make comments on the expert’s report or (as in Italy) giving a party-appointed expert the opportunity to either support or criticise the court-appointed expert’s report.

This is different from common law jurisdictions, where a party-appointed expert acts on behalf of the party from the beginning until the end of the dispute. In civil law, a party-appointed expert is used either to draft references, comment on the court-appointed expert’s report or act as an expert witness, thus making the expert relevant at different times during the dispute.

How to challenge the conclusions of a court-appointed expert

The parties have different approaches when challenging the expert’s conclusion; they can ask supplementary questions or, in a more extreme circumstance, ask for a new court-appointed expert.

When the expert hands in their report to the court, both parties have the opportunity to ask supplementary questions, if permitted by the court. By this approach, the parties can challenge the expert’s report by asking questions. Because a party-appointed expert can frame the supplementary questions, the parties have an opportunity to use the party-appointed expert to challenge the conclusions of court-appointed experts.

If there is a general dissatisfaction with the court-appointed expert’s report or their competence, there is an opportunity to get a new expert appointed. However, it is extremely difficult to get this approved by the court.

As a starting point, misunderstandings or misjudgements should be mellowed through supplementary questions so that the cost related to a new appointment is limited. In general, the appointment of a new expert is only possible if the court considers it appropriate.

Advantages and disadvantages of court-appointed experts


The use of court-appointed experts tends to facilitate an incentive for the parties to agree on settlements. As mentioned, the conclusions from a report from a court-appointed expert will often be the basis of the court’s judgment. The conclusions from the court-appointed expert in favour of one of the parties will give the parties directions on the likely outcome of the dispute. The other party is often willing to settle instead of continuing the dispute in litigation or arbitral proceedings.

In addition, the procedure for appointment of the expert ensures that an objective and independent expert acts as an expert, which raises the evidentiary value. Further, this procedure gives both parties an equal opportunity to ask the expert questions.


A concern is that inside each discipline different theoretical or methodical approaches can be preferred. This can have a considerable impact on the expert’s final decision, which leads to numerous disputes not having only one ‘right’ answer from the court-appointed expert. Consequently, a statement from the court-appointed expert will substantially depend on the choice of the expert and their qualifications.

Furthermore, judges normally do not have in-depth technical knowledge, which characterises disputes in construction law. This can lead to a concern that courts end up appointing generally qualified professionals, but not professionals with specific technical knowledge, as needed. Very often, parties themselves may have better knowledge of the required qualifications.

Finally, court-appointed experts can be a less expensive solution because only one expert is to be appointed. However, the reality is different as both parties will normally have their own expert when drafting questions to the expert and making comments on the final report, thus making the total expenses higher.


Christian Johansen is at Bruun & Hjejle, Copenhagen. He can be contacted at chj@bruunhjejle.dk.



Practical and innovative use of experts

Kim Rosenberg
Freshfields Bruckhaus Deringer, Dubai



Expert evidence is a staple feature of construction disputes – opinions given by individuals with relevant and specialist experience, qualifications or skills in the fields to which those opinions relate. Those fields can cover, for example, technical disciplines on the question of whether works are defective or complete, the amount and the cause of delays or disruption to the works, the quantum of claims, relevant industry practice or the application of local laws.

All stakeholders involved in a construction dispute should consider the role of expert evidence and how that evidence can be practically meaningful for the tribunal.1 After all, if the tribunal does not find that evidence useful in determining the issues in dispute, the expert reports will be relegated to the role of an expensive doorstop. The stakeholders for these purposes are the parties and their counsel, the tribunal and the experts themselves. So, how can expert evidence be practically meaningful for the tribunal? Does there need to be innovation in the way in which expert evidence is proffered?

This article considers two topics in addressing those questions: (1) concurrent evidence of party-appointed experts of like discipline; and (2) using quantum expert evidence to quantify the tribunal’s myriad decisions on the issues in dispute.

These are not the only topics when it comes to considering practical and innovative means of using expert evidence in construction arbitration. For example, another key topic is the use of technology, such as Building Information Modelling (BIM), in the effective presentation of complex expert evidence. However, in the interests of this article being useful to readers (as it would not otherwise suffice as a doorstop), the author has limited the content to two topics.

Concurrent evidence of party-appointed experts of like discipline

This topic is concerned with adducing evidence from experts of like discipline at the same time. That is predominantly through the form of joint statements signed by the experts and oral testimony through ‘hot-tubbing’ (vernacular with which we are all familiar but which may conjure up unappealing imagery). Concurrent expert evidence is now a common feature of construction disputes, particularly in international arbitration. This is because of the tangible benefit to tribunals in distilling the areas of agreement and disagreement in the expert evidence.

In the author’s experience, in any construction dispute there is great capacity for agreement between experts of like discipline where those experts are experienced, properly briefed, prepared and committed to being seen to be objective and independent.2 These are important caveats because unfortunately it is not always the case that experts meet these criteria, even when they hold themselves out as doing so. One need look no further than the following excerpts from decisions of the English courts on construction cases (which, unlike most arbitral awards, are public) to see that experts do not always meet the standards reasonably expected of them:3

• ‘So unbiased and irrational do I find this “expert” evidence that I conclude he failed in his duty to the court… At the end of his report, Mr [X] said he understood that duty. I do not think he did. He came to argue a case. Any point which might support that case, however flimsy, he took. Nowhere did he stand back and take an objective view as an architect…’4

• ‘I was disappointed with Mr [X] who, although an experienced expert, I felt was trying too hard to reduce the delay and other quantum heads to an insignificant level. Whether he felt, subconsciously, pressurised by [a representative of his appointing party] or not I cannot say. But his arguments were reduced to scraping the barrel in some respects… He indorsed a totally artificial calculation…’5

• ‘Mr [X] allowed himself to be used, whether wittingly or otherwise, by [his appointing party and their claims consultants] (those with the most to gain in this litigation) to act as their mouthpiece. It was almost as if they were trying to see how much of their claim they could get past Mr [X], and then Mr [Y], and ultimately the Court. It made a mockery of the oath which Mr [X] had taken at the outset of his evidence.’6

• ‘Mr [X] who was charged with the duty of independently researching and analysing these events singularly failed to take account of this documentation and the photographic evidence in his written report for the court and presented a view of the course of the critical path which was clearly wrong.’7

• ‘I reject Mr [X]’s evidence that the late design information either caused or contributed to the critical delay in the Project. His analysis was self-confessedly incomplete. He did not have the time to approach the research of this aspect of the case in the complete and systematic way, furthermore, the impacted as planned delay analysis takes no account of the actual events which occurred on the Project and gives rise to an hypothetical answer when the timing of design release is compared against the original construction programme.’8

An expert fails to meet the standard expected of them at their peril, even in private international arbitral proceedings that are shrouded in confidentiality. This is because party-appointed expert opportunities arise through word of mouth referrals. Those opportunities dry up as word spreads through the small and leaky construction arbitration community that an expert has failed to meet the standard reasonably expected of them.9

For present purposes, this article assumes the situation where experts of like discipline are experienced, properly briefed, prepared and committed to being seen to be objective and independent. In that situation, in most (if not all) construction cases, there is merit in exploring concurrent expert evidence. Some of the key issues that need to be considered are the timing for concurrent expert evidence, setting the agenda for that evidence and the particular challenges of ‘hot-tubbing’.

In relation to the first of these, the timing for commencement of the concurrent expert process, early is better. Ideally, expert engagement should commence as soon as there has been a crystallisation of the issues in dispute between the parties so the experts can then appreciate the topics that they need to address. Specifically, it is more productive for experts to start meeting to discuss their views on the relevant issues (without prejudice) before the production of their respective individual expert reports. This is because there is often an unconscious (and possibly conscious) resistance to changing position once their opinions have been committed to writing. We can appreciate the sage insight that ‘a wise man changes his mind sometimes, but a fool never’.10 However, this is more difficult to implement in practice when an expert has already issued their individual expert report and this has been disseminated to relevant stakeholders in an international arbitration. That expert will, rightly, have a sense of professional pride and will want to protect the integrity of the analyses that led to their written opinions. They will also know that any change in their opinions will be closely scrutinised by all stakeholders, including their client who is paying their invoices and, depending on the precise circumstances, that change could be used as an avenue to seek to undermine their credibility on cross-examination. That resistance can be minimised by early engagement between experts.

There is merit in going one step further and mandating in Procedural Order No 1 that experts of like discipline not only meet at an early stage, but also issue a joint statement on, at least, relevant methodology issues before any individual expert reports are filed. This reduces the risk that the experts adopt different methods of analysis that then make it difficult for the tribunal to compare their evidence and by the time those analyses are presented it is too late and disproportionate from a costs perspective to revert to alternative methods. The Society of Construction Law Delay and Disruption Protocol recognises the inherent value in early engagement on methodology between party-appointed experts:11

‘In order to avoid or at least minimise disputes over methodology, it is recommended that the parties try to agree an appropriate method of delay analysis before each embarks upon significant work on an after the event delay analysis. Failure to consult the other party on delay analysis methodology is a matter that the Protocol considers might be taken into account by the adjudicator, judge or arbitrator in awarding and allocating recoverable costs of the dispute.’

Having said that, it is important to recognise the reality of the situation that in a large and complex construction dispute, the parties may have had experts on board for months before arbitration is commenced, working up their analyses and assessing the claims. Accordingly, the risk remains that experts of like discipline are already a long way into their respective analyses using their chosen methods before the commencement of any engagement between the experts in the arbitral proceedings.

There is also merit in having a final joint statement by experts of like discipline after the individual expert reports have been filed so that the experts can effectively distil their collective evidence into a series of issues that are agreed and disagreed. That can act as a neat road map for the tribunal in navigating through the expert evidence.12

Of course, where pleadings are served in memorial style, this creates difficulty in creating a procedure where experts of like discipline start meeting before they commit their opinions (particularly on methodology) to writing. This is because the individual expert reports relied on by the claimant will be filed with the Statement of Claim – and those experts will have committed their opinions to writing at that filing date. Those opinions will be based on only part of the factual and documentary evidence, namely the evidence relied on by the claimant but not that of the defendant. Moreover, the experts on both sides will commit their opinions to writing in their individual expert reports before any document production. This situation means that there is high probability that after each expert has produced at least one of their individual reports, relevant evidence will be made available to them for the first time, which has a material impact on their analyses and opinions. The introduction of new evidence provides a sensible basis for an expert changing their opinions but, in the author’s opinion, that does not completely erode the inherent resistance to change where the expert’s opinions are already in writing.

So, when faced with memorial style pleadings, is it an option to start the concurrent expert evidence process in advance of the Statement of Claim? There are practical challenges in doing so. This is because, at that point in time, the only documents available to identify the issues in dispute are high-level summaries contained in the Request for Arbitration and Answer. These documents tend to be too brief to identify the issues in dispute to be addressed by expert evidence.

This conundrum is often one of the reasons for arguing against memorial style pleadings in a complex construction dispute, even though it may be the more common approach in international commercial arbitration. As an alternative, sometimes a hybrid pleading system is considered where the fact witness statements accompany the pleadings but the expert reports are filed later. This approach can be a sound compromise depending on the precise circumstances.

The next issue for consideration is the agenda for the concurrent expert evidence process. What are the experts to discuss? What issues will they opine on in their joint statements? In appropriate cases, there is merit in legal counsel agreeing the joint instructions to experts of like discipline. After all, they will have a good handle on the issues in dispute in the arbitration and are often best placed to surgically formulate key questions for the experts, with the objective of ending up with a distillation of the expert evidence relevant to those issues in dispute.

The alternative is to leave it to the experts to agree on their agenda. As the individuals most familiar with the expert issues, they should know how to frame the questions to be answered in the joint statements to distil the expert evidence. Unfortunately, that is not always the case. If the experts cannot agree on their agenda, this responsibility will necessarily fall back onto legal counsel or, in challenging situations where legal counsel also does not agree, the tribunal.

The final consideration for this article in relation to concurrent expert evidence is ‘hot-tubbing’. This is a process by which experts of like discipline are both sworn in and give oral evidence together. There are numerous variants on the actual procedure (such as whether the tribunal leads the questioning or this is left to legal counsel). Hot-tubbing is increasingly requested by tribunals dealing with complex construction disputes. It allows them to understand the views of experts of like discipline in real time, rather than hearing one expert on all issues and then waiting for hours or potentially days during the merits hearing to understand the views of the counterpart expert on a particular issue, by which time they have been distracted by lots of other issues. Hot-tubbing also can be a powerful tool for tribunals in educating themselves on pertinent matters that are not clear from the evidence on t