Expert evidence is often required in construction disputes and is intended to assist the court when it is asked to consider matters that it does not have a sufficient degree of knowledge on. Frequently construction disputes can require more than one expert, although the use of expert evidence is restricted to that which is reasonably required to resolve the dispute.
The overriding duty of the expert witness is to assist the court on the matters within their expertise. This duty supersedes the expert’s duty to the party instructing them.
The role of the expert can therefore prove an exercise of balancing the expectations of the party who has instructed them with their overriding duty to the court.
Types of expert witnesses
A single expert witness is appointed to act for one party in a dispute. A single joint expert witness is jointly appointed either by the court or by all parties to a dispute to provide evidence on a particular issue on which all the parties to the dispute wish to submit expert evidence (see Instructing an expert).
An expert witness is not the same as an expert adviser. The obligations of an expert witness and expert adviser differ substantially in relation to duties, privilege (see Expert reports) and communications with parties.
In civil proceedings, expert evidence is given by an expert witness. The expert witness’ overriding duty is to the court. The evidence is normally an opinion based on fact, although it can be relevant to establishing the primary facts of the case. The evidence will either be in the form of a written report, which is prepared before the trial and made available to all parties to the litigation, or as oral evidence from the expert witness during the trial.
An expert adviser advises a party on a specialist matter within their expertise at any stage of the dispute. This can be useful at an early stage in assessing the strengths of the case, deciding whether to pursue the matter and understanding what investigations may be required.
The advice provided by an expert adviser at this stage will be privileged (Carlson v Townsend  EWCA Civ 511). However, until the court has given permission for the use of the expert adviser, their costs may not be recoverable. There is also a risk that the expert adviser cannot be used later on as an expert witness as they are no longer regarded as independent (see also Privilege).
Duties of experts
Civil Procedure Rules (CPR), part 35.3 provides that, when an expert witness is instructed to give or prepare evidence for the purpose of civil proceedings in England and Wales, then it is their duty to assist the court on all matters within their expertise and that this duty overrides any obligation to the person from whom the experts have received instructions or by whom they are paid.
Separately, expert witnesses owe a duty to exercise reasonable skill and care to the party who has instructed them and to also comply with their professional code of ethics, but these duties are subject to the expert witness’ overriding duty to the court (paragraph 9, Civil Justice Council Guidance for the instruction of experts to give evidence in civil claims (CJC guidance)).
Single joint experts also have an overriding duty to the court (paragraph 43, CJC guidance). A single joint expert has been jointly appointed by all the parties to the dispute and so will owe an equal duty to all parties and must maintain independence, impartiality and transparency at all times. They should not attend any meeting or conference which is not a joint one unless all the parties have agreed in writing or the court has directed that such a meeting may take place and who is to pay for the expert’s fees for the meeting.
Duties and responsibilities
The key duties and responsibilities of expert witnesses are set out in CPR practice direction (PD) 35 para 2.1. This summarises the case law in this area which includes the landmark case of National Justice Compania Naviera SA v Prudential Assurance Co Ltd (The ‘Ikarian Reefer’)  2 Lloyd’s Rep. 68 in which Mr. Justice Cresswell listed 7 duties and responsibilities of expert witnesses in civil cases, which include the following:
- expert evidence presented to the court should be, and should be seen to be, the independent product of the expert uninfluenced as to the form or content by the pressures of litigation (Whitehouse v Jordan  1 WLR 246, HL). A useful test of ‘independence’ is whether the expert would express the same opinion if given the same instructions by another party (paragraph 10, CJC guidance);
- an expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within their expertise (Pollivitte Ltd v Commercial Union Assurance Company Plc  1 Lloyd’s Rep. and Re J (1991) FCR 193);
- an expert witness in the High Court should never assume the role of an advocate nor should they take it upon themselves to promote the cause of the party instructing them;
- an expert witness should state the facts or assumption on which their opinion is based. They should not ignore material facts which could potentially change their initial opinion (Re J (1991) FCR 193);
- an expert witness should make it clear when a particular question or issue falls outside their expertise (Anglo Group plc v Winther Browne & Co Ltd 72 Con. LR 118);
- if an expert’s opinion is not properly researched because they consider that insufficient data is available then this must be stated with an indication that the opinion is no more than a provisional one (Re J (1991) FCR 193). If the expert who prepared the report cannot assert that the report contains the truth without qualification then this should be stated in the report (Derby & Co Ltd v Weldon (No. 9), The Times, November 9, 1990 CA);
- if, after exchange of reports, an expert witness changes their view on the material for any reason, then such change of view should be communicated (via their legal representative) to the other side without delay and when appropriate to the court (Anglo Group plc v Winther Browne & Co Ltd 72 Con. LR 118);
- where expert evidence refers to photographs, plans, calculations, analyses, measurements, survey reports or other similar documents, these must be provided to the opposite party at the same time as the exchange of reports;
- expert witnesses also have a duty to assist the court so as to allow it to deal with cases in accordance with the overriding objective (CPR 1.1) which provides that courts must deal with cases justly, proportionately, expeditiously and fairly (paragraph 11, CJC guidance). However, this does not mean that they should engage in the role of advocates or mediators nor does it require them to trespass on the role of the court in deciding facts.
In many cases expert evidence is crucial to the outcome of a case and failing to follow these duties and responsibilities can lead to serious criticism by the court. In the case of Van Oord Ltd v Allseas UK Ltd  EWHC 3074 the claimant’s quantum expert had effectively allowed himself to become the claimant’s mouthpiece, and the court dismissed his evidence as ‘entirely worthless’. Just as the Ikarian Reefer provided guidance as to what an expert should do, this case provides guidance as to what an expert should not to do; in fact in certain areas the expert did the complete opposite of what the court expected of an independent expert. So an expert should:
- make sure not to take the pleaded claims on face value without checking the underlying documents that support or undermine them;
- consider all of the witness statements produced by both parties not just the evidence from one side;
- be prepared to value claims on alternative bases or subject to other assumptions apart from the full basis of the claim;
- not rely on made up or calculated rates or assumptions but know the actual costs incurred;
- critically analyse points raised by opposing experts and address them early;
- be prepared to stand by his or her expert report, and be sure that all parts can be justified;
- ensure expert reports are drafted clearly so that they do not confuse or mislead;
- check the accuracy and detail of all documents referred to and appended to the expert report;
- ensure that all views expressed are the experts’ own view, not based on the views of others, or (where necessary) attribute the views to others;
- be clear whether documents and analysis relied on has been prepared by others and the extent to which their accuracy has been checked;
- check the claims made, rather than reciting information told by others; and
- cross refer the value of the claims with alternative methods of calculations (such as reasonable rates) and alternative approaches to ensure the figures are fair and reasonable.
In Bank of Ireland v Watts Group  EWHC 1667 (TCC), the bank’s expert was unreliable. The bank had a close relationship with the expert since the bank had provided the majority of the expert’s work and fees in recent years, which led to the expert adopting an unrealistic approach to the allegations in the case and unreasonable intransigence. The court concluded that the expert was not a properly independent witness, and had failed to comply with the duties set out in The Ikarian Reefer. Particular criticism was made of the expert’s ‘blatant misuse’ of certain RICS guidance by the deliberate omission of words from the source so as to present a position on a false basis, something which was clearly contrary to the expert’s duty to the court.
Consequences of failure to comply with duties
The consequences of an expert witness’ failure to comply with their duties and responsibilities will depend upon the facts of the case.
The CJC guidance (Paragraph 15) provides that any failure on the part of the expert witness to comply with the CPR or court orders or any excessive delay for which they are responsible may result in the parties who instructed them being penalised or even debarred from placing the expert’s evidence before the court.
The section on sanctions in the CJC guidance at paragraphs 89-92 warns that the sanctions may not only be limited to cost penalties and, if proceedings have not started, may include a professional instructing an expert or an expert may be subject to sanction for misconduct by their professional body/regulator (paragraph 90). If proceedings have started, sanctions may include cost penalties, the expert’s report being held to be inadmissible, (in extreme cases) contempt of court, (in cases of perjury) criminal sanction and a claim on the expert’s professional indemnity insurance.
Failure may lead to an order for costs being made directly against the expert witness (see the case of Phillips v Symes  EWHC 2330 (Ch) where it was held that the court could make an order for costs (under s51 of the Senior Courts Act 1981) directly against the expert witnesses who by their evidence cause significant expense to be incurred and do so in a flagrant and reckless disregard of their duties to the court).
Instructing an expert
At the start of the dispute the parties should consider whether there is a need for an expert witness to assist the court. Paragraph 4 of the CJC guidance provides guidance to help determine whether expert evidence is necessary. This includes taking account of the principles set out in Civil Procedure Rules (CPR) parts 1 and 35 and in particular whether ‘it is required to resolve the proceedings’.
The underlying objective of restricting expert evidence is set out in the White Book notes at paragraph 35.1.1 as being to reduce the incidence of inappropriate use of expert evidence. In the TCC decision of Wattret v Thomas Sands Consulting  EWHC 3455 (TCC) the Court decided that expert evidence in a case alleging negligence against a firm of chartered quantity surveyors was necessary but that it needed to be closely controlled to avoid experts providing:
‘swathes of commentary on each communication passing between the parties, giving their own slant or interpretation of what happened and what ought or ought not to have been advised.’
In some cases where expert evidence is not entirely necessary but would be of assistance a balance needs to be made by the court as to the assistance it will provide the court and the proportionality of its admission (British Airways plc v Spencer  EWHC 2477 (Ch)).
Section 13.2 of the TCC Guide also provides guidance on instructing expert witnesses in TCC disputes. It emphasises that as TCC disputes normally involve expert witnesses, given the cost of preparing evidence, the parties and the court must, from the earliest pre-action phase until the conclusion of the trial, use experts effectively and proportionately. The scope of expert evidence must be limited to what is necessary for the requirements of the case. The guide adds that, when considering an application for permission to call an expert, the court should be provided with estimates of the experts’ costs and its court’s permission may limit the issues to be considered by the experts. Such a limitation should be linked to the party’s cost budget.
Selecting an expert witness
Before experts are formally appointed or the court’s permission to appoint named experts is sought, the parties should consider whether they wish to submit expert evidence on a particular issue. If this is the case, then the parties should consider agreeing to give joint instructions to a single expert. CPR part 35.7 provides that in these circumstances, the court may direct that the evidence on this issue is given by a single joint expert. If the parties cannot agree who should be the single joint expert then the court may either select the expert from a list prepared by the parties or direct that the expert be selected in such other manner as it may choose to direct.
The CPR positively encourages the use of single joint experts to the extent that section paragraph 34 of the CJC guidance states that, wherever possible, a joint report should be obtained. Section 13.4.2 and 13.4.3 of the TCC Guide provides useful guidance as to when a single joint expert will likely be appointed in TCC disputes. For example, single joint experts are unlikely to be appropriate for the principal liability disputes in a large case or where considerable sums have been spent on an expert at a pre-action stage or where the issue involves questions of risk assessment or professional competence. However, they may be appropriate:
- in low value cases where technical evidence is required but the cost of adversarial expert evidence is likely to be very high;
- where the issue is separate and self-contained;
- where there is a subsidiary nature which is relatively uncontroversial to resolve; or
- where a test is required which could be done in a laboratory on behalf of all parties.
Paragraph 16 of the CJC guidance provides a useful checklist for the parties to consider to when selecting an expert. Consider:
- whether the expert has the appropriate expertise and experience;
- whether the expert is familiar with the duties of an expert;
- whether the expert can produce a report, deal with questions and have discussions with other experts within a reasonable time and at a cost proportionate to the matters in issue;
- whether the expert is available to attend the proceedings;
- whether there is a conflict of interest;
- whether the expert will write the report themselves or be assisted by a team;
- the likely independence of the expert; and
- the expert’s location.
Appointing an expert
The terms of the expert’s appointment should be set out in a retainer letter executed by both parties. Paragraphs 17 and 18 of the CJC guidance provide guidance on what terms should be included in the appointment and include items such as the capacity in which the expert is appointed and the services that they are to provide. The terms of the retainer letter are likely to be privileged and so should be kept separately from the instructions to the expert (which are not privileged) (CPR part 35.10(4)).
If it is agreed that the appointment of a jointly instructed expert would be beneficial then, aside from the provisions contained in CPR parts 35.7 and 35.8, the guidance in paragraph 33 of the CJC guidance and section 13.4 of the TCC Guide, the parties should attempt to agree joint instructions as far as possible. This should include the documents that are to form the basis of the expert’s instructions. If agreement cannot be reached, the expert should be made aware of any areas of conflict that remain in the parties’ instructions. A jointly appointed expert should ensure that both parties are kept aware of any material developments by copying both sides in on all communications.
Formal appointment by court
Even if the parties have already appointed experts, they cannot call an expert witness or put in evidence an expert’s report without the court’s permission (CPR 35.4). This is because the court has complete control over evidence and will restrict it to that which is necessary to resolve the proceedings justly (CPR 32.1).
If a party wishes to call an expert witness then they must provide an estimate of the costs of the proposed expert evidence, identify the field in which the expert evidence is required, the issues which the expert evidence will address and (if practicable) the name of the proposed expert. CPR 35.7 provides further guidance on the factors that the court will take into account when considering whether to give permission for the parties to rely on expert evidence. It will consider whether it is proportionate for the parties to have separate experts and whether the instruction of a single joint expert is likely to assist the parties and enable the court to resolve the issues more quickly.
In giving permission for the use of expert evidence, the court will normally order the exchange of such evidence with a definition of the parameter of the expert’s area of expertise and a clear description of the issues about which that expert may give evidence (Section 13.3.5, TCC Guide). The order granting the permission may specify the issues which the expert evidence should address.
Formally appointing an expert witness takes place after the court has considered the necessity for, and scope of, expert evidence at the first case management conference. Parties should try to avoid incurring expert evidence costs before the first case management conference on uncontroversial matters or in relation to matters where a single joint expert is likely to be appointed (Section 13.3, TCC Guide). Even if a single joint expert is not appointed, wherever possible, the parties’ experts should cooperate fully with one another.
Prior to the initial case management conference and initial pre-action protocol meeting, parties should, if possible, disclose initial reports to each other on a without prejudice basis to assist in defining the issues in dispute and saving costs (Section 13.3, TCC Guide).
Before and at the first case management conference and at each subsequent pre-trial stage of the action, the parties should consider the items listed at Section 13.3.4 of the TCC Guide. These include:
- the number, disciplines and identity of the expert witnesses they are considering instructing as their own witnesses or as single joint experts;
- the precise issues the expert is expected to address; and
- the timing of any meeting, agreed statement or report, any appropriate investigations that could be undertaken jointly or in collaboration with other experts, any common methods which should be adopted by all experts and the availability of experts to carry out the tasks assigned to them.
The court will give directions insofar as the parties cannot agree the above matters (Section 13.3.5, TCC Guide).
Paragraph 20 of the CJC guidance provides guidance on what an expert’s instructions should include. Instructions should be clear and include information such as the purpose of requesting the report, whether proceedings are being contemplated and the statements of case (if any).
CPR part 35.8 and paragraphs 38 to 41 of the CJC guidance provide guidance on instructions to single joint experts. The starting point is that the parties should try to agree instructions to the single joint expert; however, if they cannot agree then any party may send instructions to the expert, ensuring that a copy is also sent to the other relevant parties in the dispute.
If the parties cannot agree the joint instructions they should try to agree on where the areas of disagreement lie and their instructions should clearly identify such areas of disagreement. The terms of appointment should make clear that (unless the court otherwise directs), the relevant parties will be jointly and severally liable for the payment of the expert’s fees and the expert should be provided with a copy of any order limiting expert fees and expenses.
In order to assist the expert, the instructing solicitors should prepare a brief, which should include the following:
- the party making the appointment and the parties to the proceedings;
- the subject matter;
- the nature of proceedings;
- the timetable fixed in any proceedings, and
- the current status;
- the status of any action that has commenced, with relevant documents in which the parties state their case (although a great deal of care needs to be taken when doing this as it may compromise the documents’ privilege (see Privilege));
- details of other experts appointed by the party making this appointment, and by other parties, if known, with a note of these experts’ fields of expertise;
- in large or complex cases, the method by which the experts are to coordinate their services, where appropriate;
- specific issues on which the expert is asked to advise;
- the timescale in which the expert is asked to prepare the report (this may be fundamental to the expert’s acceptance or refusal of the instructions); and
- details of key documentation which the expert should review.
Contents of reports
Expert evidence is generally given by way of a written report, unless the court says otherwise.
Under part 35.10 of the Civil Procedure Rules (CPR), it is clear that an expert report must contain certain information in order for it to be admissible as evidence in court. The exact requirements are set out in the Practice Direction accompanying CPR part 35 (PD 35), which provides that an expert report must:
Be addressed to the court: It should be clear that the expert has written their report for the benefit of the court, and not the party who instructed them.
State the expert’s qualifications:
- This will include academic and professional experience, but also anything else the expert considers relevant to clarify why they have the relevant knowledge and experience to provide a specialist opinion. This is usually achieved by appending a CV to the expert report;
- Provide details of any literature or material which the expert has relied on in formulating their opinion;
Summarise the substance of all material facts and instructions relied upon:
- This allows the court to understand:
the exact question the expert was asked to answer; and
- the facts they relied on (which might ultimately shape the report, particularly if the opponent has taken a different interpretation of the facts).
In relation to the expert’s instructions, care should be taken to ensure that the brief is accurately described in the expert report so as to avoid the full instructions becoming discloseable to the court;
Make clear which facts stated in the report are in the expert’s own knowledge: This is particularly relevant to highlight which opinions are based on assumptions, or information provided by third parties. If an assumption has been used, the expert should explain why reliance on that assumption is considered reasonable;
Say who carried out any investigations: If any experiments, measurements, calculations, examinations etc, have been relied on in the report, it must be clear whether these were performed by the expert, or whether these were carried out by another person. If another person’s work has been referenced in this way, the report should include details of their relevant qualifications, and state whether the investigations were carried out under the expert’s supervision;
Provide the range of possible opinions: If there are a number of possible explanations for the facts, or interpretations of the information available, the expert report should summarise the full range of explanations and interpretations. In reporting the findings, the expert should identify why they have reached the opinion they have in view of the range of possible explanations.
Contain a summary of the conclusions reached;
Explain any relevant qualifications: If it is necessary to qualify their opinion (i.e. by stating that certain information was not available or if certain assumptions had to be made), these should be explained clearly;
Contain a declaration to the court: The expert’s overall duty is to the court, and therefore the expert report should state that the expert understands and has complied with that duty;
Acknowledge the CJC guidance: The report should clearly state that it has been compiled with reference to CPR part 35, the accompanying practice direction and the CJC Guidance.
Contain a statement of truth: Using the following wording:
‘I confirm that I have made clear which facts and matters referred to in this report are within my own knowledge and which are not. Those that are within my own knowledge I confirm to be true. The opinions I have expressed represent my true and complete professional opinions on the matters to which they refer.’
Be signed and dated by the expert: This should include a statement of truth that the expert believes all of the report’s contents to be true, subject to any qualifications already provided.
Use of draft reports
In the absence of official guidance in the Civil Procedure Rules (CPR), the court held in Jackson v Marley Davenport Limited  EWCA Civ 1225 that earlier drafts of an expert report were privileged, and therefore not disclosable to the court. This position was taken on the basis that earlier drafts were not intended to be relied on at trial. For further information on the privilege attached to draft reports, see Privilege.
Practical tip on the use of draft reports
In their final report, the expert should not refer to earlier drafts of their report. Referring to earlier drafts may remove the privilege attached to those drafts and make them disclosable to the court by virtue of CPR part 35.10 (4).
Supplemental statements by experts
In some circumstances it may be necessary for an expert to amend or supplement their report. In general, these will only arise if a point raised at trial has been missed by the expert in their original report, evidence has been raised at trial which affects the opinion given, or because the report should reflect the outcome of a meeting between joint experts. If a report does have to be supplemented in this way, an expert should inform their instructing solicitors, and ensure that each supplemental report or addendum is signed and dated.
It will not always be the case that a report should be updated to reflect the outcome of a meeting of the joint experts, as this can be done by way of the joint statement.
Once a witness statement has been disclosed, CPR part 35.6 allows a party to submit written questions to their opponent’s expert in order to seek clarification of the report. These questions must be submitted within 28 days of the report being issued, and a question can only be put to an expert once (except with the court’s permission). It is important to note that any answers provided by the expert then become part of their report.
For the purposes of the CPR, ‘clarification’ is not explained, but it is generally accepted that a question will be for more than clarification if it requires an expert to carry out new investigations (Mutch v Allen  EWCA Civ 76 at first instance). However, in the case of Mutch v Allen, it was ultimately decided that the question presented to the expert was important for the determination of the case, and therefore said that further evidence would be necessary (possibly in person, at trial).
Although it is possible for an expert to refuse to answer a question, it should be noted that this can result in the court ordering that the expert report can no longer be relied upon as evidence.
Consequences for failure to disclose an expert report
CPR part 35.13 makes it clear that if an expert report has not been properly disclosed, it cannot be relied upon in court, and the expert in question cannot be asked to give oral evidence in court (unless, in both instances, the court gives permission).
The court may direct expert witnesses to identify and discuss issues relating to the case, with the aim of reaching an agreed opinion on certain issues, either identified between them or decided by the court. This may be with a view towards the production of a joint statement which demonstrates their agreed views and any remaining disagreements which they hold over issues, including reasons for this disagreement.
The ordering of discussions between experts and the production of a joint statement is at the discretion of the court, however within the TCC it is seen as a useful tool of the court and is generally included within the court’s directions. Most importantly these discussions will be without prejudice and, as directed in CPR part 35.12 (4):
‘The content of the discussion between the experts shall not be referred to at the trial unless the parties agree’.
Therefore any interference in their discussions and subsequent statement, either through an attempt to influence the expert witness or the proof reading of the statement before release, is inappropriate. If problems were to occur from the discussions and joint statement, it may be suitable to either gain permission to ask additional questions or to call the expert in to provide oral evidence.
Any agreement made by the expert witnesses in the course of their discussions or statement is not binding, unless agreed by both parties beforehand (CPR 35.12 (5)). However, although not binding, such agreements will serve as guidance for the courts to rely upon.
The joint statements on the other hand are not privileged and will be available to the court and parties unless the parties have agreed otherwise. The fact that joint report was made during mediation does not make it privileged for the purposes of litigation. Thus, if you do not wish for the joint statement to be available at litigation it is advisable to ensure that the relevant agreement is reached with the opposing party and such requirement is written into the court order.
Practical tips for experts’ discussions
Consider these points during experts’ discussions:
reference should not be made at trial to what was said during expert’s discussions;
seek permission to ask additional questions to experts after the discussion between the experts or call an expert to give oral evidence in case you notice discrepancies between your expert’s report and the joint statement;
experts should not ask their instructing solicitors to proof read or otherwise assess their joint statements before it is signed;
remember to take appropriate measures in case you wish for a joint report from mediation to be treated as privileged at litigation.
An expert must include an accurate and complete statement of substance of all material instructions in their report (CPR 35.10(3)). (It is advisable to keep a retainer separate from the instructions as the requirements of CPR part 35.10(3) do not apply to retainers).
Although instructions are not privileged, the court is unlikely to order their disclosure unless there are reasonable grounds to consider that the expert’s statement provides incomplete or inaccurate account of instructions given (CPR 35.10 (4)).
One of the main risks associated with disclosing instructions is being ordered to disclose any material documents which form part of the instruction, regardless of whether such document may otherwise be privileged (for example, draft witness statements or the draft report). The leading case in this area is Morris v Bank of India  ChD, which gives the courts power to order disclosure of the documents to the extent necessary for establishing what underlying facts and assumptions the expert was provided with for the purposes of the report.
Practical tips when reviewing an expert’s report
ensure that the expert provides a full and accurate statement of the substance of all material instructions that have been provided to them;
check that report does not contain any references suggesting that the expert has seen a document on which they have based their opinion, but which was not included in their statement of instructions;
do not provide experts with privileged documents and, if this does happen, make sure that the document is listed among the documents forming part of the expert’s material instruction in the summary of instruction.
Do earlier drafts of the expert report remain privileged?
Judgment in Jackson v Marley Davenport Ltd  EWCA Civ 1225 suggests that earlier drafts, final reports which have been prepared for the legal advisers and subsequent reports not relied upon remain privileged. However, experts should avoid referring to earlier drafts in their reports as they may be subject to a disclosure order by virtue of CPR part 35.10 (4).
Disclosure of documents referred to in the expert report
Although CPR part 31.14(2) entitles a party to apply for an order for inspection of any documents mentioned in the expert’s report, such right is limited to documents which do not form part of the instruction. Provided that an expert has complied with CPR part 35.10(3) the court will have no grounds to order disclosure of the instructions or of any specific documents which form part of the instruction.
However, if the report makes a reference to a document which is not part of the instruction then the other side will be entitled to inspect such document by virtue of CPR part 31.14(2).
Disclosure by a party ordering a report
If a party has already disclosed a report prepared by the original expert, then if it chooses to instruct another expert (substitute expert) to prepare a further report there is no obligation on it to disclose the substitute report if it does not intend to rely upon it.
If a party decides not to use the original expert report and needs permission to rely on the report of the substitute expert, the court will usually impose a condition for the grant of that permission that the party waive privilege in the original expert’s report and disclose it. Permission may be required from the court, for example, where there is an existing order naming the original expert and that order will have to be varied to enable reliance on a different expert in the same field (see Beck v Ministry of Defence  EWCA Civ 1043, Hajigeorgiou v Vasiliou  EWCA Civ 236 and Lee v Colchester Hospital University NHS Foundation Trust  EWHC 1766).
However, the position of the courts appears to be different in relation to expert advisers whom a party may instruct independently and at its own expense (Edwards-Tubb v JD Wetherspoons PLC  EWCA Civ 136).
The court generally discourages the practice of ‘expert shopping’ for a more favourable expert opinion and can impose terms requiring disclosure of not just the original expert’s report but other documents, such as attendance notes, where a party provides strong evidence of any ‘expert shopping’ (BMG (Mansfield) Ltd v Galliford Try Construction Ltd  EWHC 3183 (TCC) and Allen Tod Architecture v Capita Property and Infrastructure  EWHC 2171 (TCC)).
Use of the report by other parties
CPR part 35.11 provides that ‘where a party has disclosed an expert’s report, any party may use that expert’s report as evidence at the trial’. A party is entitled to use the report produced by the other party’s expert if the court’s permission to use this report in the proceedings has been permitted as required by CPR part 35.4(1).
Practical tips when ordering a substitute report
if a party wishes to rely on the report of a substitute expert, permission to do so will be subject to condition that the original expert’s report is disclosed;
be aware that the original expert could be instructed by the other party and used as its witness;
the original expert is entitled to go to court to explain their view as to why they have been dis-instructed.
An expert adviser can be instructed at party’s own expense at any stage of a dispute and such instruction will not be governed by CPR part 35.
As opposed to the report produced by the court’s expert, a party is not required to disclose the report produced by the expert adviser should it wish to order a second report. However, care should be taken if the expert adviser later becomes your expert witness as the court may in certain cases have discretion to order disclosure of instructions and advice.
Historically experts enjoyed full immunity from being liable for the contents of their report (also known as ‘immunity from suit’). However, however such immunity has gradually eroded and was effectively taken away in 2011.
In 1992, the decision in Palmer v Durnford Ford  QB 483 refined the focus of immunity from suit to only the work that was preliminary to providing evidence in court. This meant that work done to advise the client, such as commercial advice regarding the merits of a case or pre-litigation advice, was not covered by immunity. This limitation to immunity was then extended by a further 2 cases.
In the ruling of Phillips v Symes (No 2)  EWHC 2330 (Ch), experts were made liable for costs if they were found to have ‘acted recklessly or in flagrant disregard of his duties to the Court’, and the consequence of their actions were coverable by costs. Later the judge in General Medical Council v Meadow  EWCA Civ 1390 ruled that experts could not enjoy immunity to disciplinarily procedures if they demonstrated ‘serious professional misconduct’ in court.
The case of Jones v Kaney  UKSC 13 finally removed an expert’s immunity from suit. It was deemed that there was no conflict of duties between the client and the court for an expert as when they are retained, and in CPR part 35.3, their overriding duty to the court is made clear. Therefore it was decided that removing this immunity would not cause reluctance among experts to speak impartially, while allowing justice when a breach of duty to the client is made.
Expert witnesses are still immune from suit brought by the opposing party and, like all those involved in litigation, from claims in defamation. However, they are now open to claims such as disciplinary procedures, wasted costs claim (as long as the expert is deemed to have ‘acted recklessly or in flagrant disregard of his duties to the Court’ Phillips v Symes (No 2)  EWHC 2330 (Ch)), criminal prosecution for perverting the course of justice or contempt of court and perjury and breach of duty.
Practical tips when assessing immunity of an expert
it is important to inform the experts that the cost order may be made against them by referring them to the relevant section of CPR part 35.3 or declaration that they must sign;
it is vital that experts accept only clear and unambiguous written instructions. This is particularly important when consideration is given to the requirements of the CPR;
while primarily the obligation of those instructing the expert, the expert should nevertheless try to ensure that they have been provided with sufficient information to assess whether the issues as identified are matters upon which they are competent to act as an expert witness;
the expert will need to satisfy themselves that no conflict of interest exists. It is fundamental, in order to preserve independence, that any connection with any of the parties is disclosed immediately;
from a practical standpoint, the expert should make clear the basis upon which they wish to charge. However, note that in accordance with CPR part 35.8(4)(a), the court may, before an expert is instructed, limit the amount that can be paid by way of fees and expenses to the expert;
the test for expert’s negligence to found liability for costs is narrow. Redress may be available for an aggrieved party in the form of costs order against the expert if they are found to have acted recklessly or in flagrant disregard of their duties to the court.
Concurrent evidence or hot tubbing
The TCC Guide (section 13.8.2, 4th bullet point) encourages expert evidence to be given concurrently (this method is also known as ‘hot tubbing’). Basically, this is a method of giving evidence where both experts give evidence at the same time and the court chairs a discussion between them.
The idea is that this method makes it more likely that the experts will reach agreement on certain issues or at least make concessions. CPR PD 35, paragraph 11 currently provides that hot-tubbing is an option in all civil proceedings and the court will now have the power at any stage of proceedings to direct that experts give their evidence concurrently. The court may direct that an agenda be prepared, based on the areas of disagreement in the experts’ joint statement and that at the hearing the experts will answer questions on those areas in a discussion which may be initiated by the judge.
In 2016, the Civil Justice Council (CJC) published its report on concurrent evidence with a number of recommendations encouraging the use of hot tubbing. Following that, in June 2017 the Civil Procedure Rule Committee approved changes to CPR PD 35 which were ‘not as radical as the CJC may have hoped.’ The approved PD 35 sets out a revised procedure to be followed where hot tubbing is to be used, and additionally enables the court to direct the evidence to be given in any appropriate manner including on an issue-by-issue basis where an expert gives evidence and is cross-examined on an issue followed sequentially by the other experts giving evidence in relation to the same issue.
In the case of SSE Generation Ltd v Hochtief Solutions AG  ScotCS CSOH 177, a case involving the collapse of a tunnel at a hydroelectric scheme, Lord Woolam highlighted the benefits of concurrent evidence which the judge found to be ‘an extremely valuable exercise’. The most successful session involved the 6 tunnelling experts and the benefits included the judge being able to hear the different opinions at one and the same time as opposed to weeks apart and to form an assessment of the quality of the evidence, and for the experts themselves to be able to challenge each other’s opinion which enabled all parties to focus on the main issues.
The case also highlighted that hot-tubbing is less successful in cases where there is little common ground between the experts.