19. The Role of the Expert Witness in Professional Negligence Litigation

Gerald F Hanretty QC

A. Introduction

Expert or skilled witnesses are objectionable. Needless to say, that observation is not directed towards the characters, qualities, learning or experience of those not infrequently called to assist parties and the court in litigation. Rather, the leading of such evidence necessarily results in material being presented to the court which is, by its nature, opinion evidence and accordingly objectionable – and, in the absence of justification, therefore inadmissible.

Issues in relation to the admissibility and use of opinion evidence have long been the subject of debate throughout the English-speaking world. Indeed, in the 21st-century it is worthwhile reflecting upon the observations of J P Taylor in the third edition of his work A Treatise on the Law of Evidence:1

Perhaps the testimony which least deserves credit with the jury is that of skilled witnesses. These gentlemen are usually required to speak, not to facts but to opinion; and when this is the case, it is often quite surprising to see with what facility, and to what extent, their views can be made to correspond with the wishes or the interests of the parties who call them.

It is likely to be the position that such an observation would be thought by most to remain valid, at least in part. However, what has not much been discussed is the role of the expert in modern dispute resolution other than analyses of the principles to be adopted by experts in the conduct of their duties with only a little practical guidance for practitioners in relation to the choice of experts.

B. The Conventional Analysis

Although litigation by its nature puts in issue partisanship on the part of expert witnesses, in reality, those giving evidence within the realm of professional negligence litigation are highly regarded. In a relatively small jurisdiction like Scotland, it is unsurprising that professional integrity, impartiality and sound judgement are highly prized. Accordingly, challenges to skilled witnesses are most often advanced by challenging the empirical material upon which opinions are advanced or by denouncing the expert opinion as an exercise in usurping the function of the court itself. The importance of instructing expert witnesses who command respect from within their professions cannot be overemphasised.

Of course, the Court jealously guards the role society calls upon it to perform. The classic exposition of the expert’s function might be found in the familiar guidance provided by Lord President Cooper in Davie v Magistrates of Edinburgh.2

More recently, it appears to have been thought necessary to elaborate upon the role of the expert witness. Although discussed within the context of a criminal appeal the observations made in Wilson v HM Advocate3 provide general guidance on the matter. It is worthwhile considering at length the court’s opinion in relation to expert evidence in its adoption of Lord President Cooper’s dicta and its application in a more modern context:4

At this point, in view of the significance of (certain) testimony in this case, we should now consider what we believe to be the proper character of expert evidence, and in particular attempt to describe our understanding of its nature and effect on the conclusions we should draw. In general, of course, opinion evidence is not admissible in our criminal courts; witnesses may only under normal circumstances give evidence about matters within their direct knowledge. The evidence of an expert witness is an exception to this rule. It is not possible to provide an absolute direction as to what constitutes legitimate subject-matter for expert opinion. However, two general principles will normally give some guidance. First, the subject-matter under discussion must be necessary for the proper resolution of the dispute, and be such that a judge or jury without instruction or advice in the particular area of knowledge or experience would be unable to reach a sound conclusion without the help of a witness who had such specialised knowledge or experience. Secondly, the subject-matter in question must be part of a recognised body of science or experience which is suitably acknowledged as being useful and reliable, and properly capable of reaching and justifying the opinions offered, and the witness must demonstrate a sufficiently authoritative understanding of the theory and practice of the subject. The nature and scope of expert opinion evidence cannot at any one point in time be exhaustively defined.

The effect of expert opinion evidence can perhaps be described with more precision. The role of the expert witness, and his duties and responsibilities, have been subject to much judicial comment. In National Justice Campania Naviera SA v Prudential Assurance Co Ltd (The Ikarion Reefer),5 Cresswell J listed a number of such duties and responsibilities, inter alia:

1. 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 exigencies of litigation.

2. An expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise.

3. An expert witness should state the facts or assumptions on which his opinion is based. He should not omit to consider material facts which could detract from his concluded opinion.

4. An expert witness should make it clear when a particular question or issue falls outside his expertise.

To this might be added a requirement that an expert witness should in particular explain why any material relevant to his conclusions is ignored or regarded as unimportant. Although the categories of duty and responsibility described by Cresswell J in the Ikarion Reefer case were concerned with civil matters, these rules are equally applicable to criminal cases.

In addition, particularly in criminal cases, other duties and responsibilities have been recognised by the courts. For example, the court will expect in a criminal matter that an expert’s report must state the facts upon which opinions are based, and if assumptions are made, these must be clearly identified. Reasons must be given for conclusions. Whether instructed for the prosecution or defence, the principal duty of an expert witness is to the court, and this overrides any duty he owes to the party which instructed him. Again, explanations should be given for the basis on which all relevant material is either accepted or rejected.

It therefore follows that a judge or jury is not bound by the opinion evidence tendered by an expert witness. There are clear principles under which such evidence is admitted. In Davie v Magistrates of Edinburgh Lord President Cooper said (p 40):

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 … Their duty is to furnish the Judge or jury with the necessary specific scientific criteria for testing the accuracy of their conclusions so as to enable the Judge or jury to form their own independent judgment by the application of these criteria to the facts proved in evidence. The scientific opinion evidence, if intelligible, convincing and tested, becomes a factor (and often an important factor) for consideration along with the whole other evidence in the case, but the decision is for the Judge or jury. In particular the bare ipse dixit of a scientist, however, eminent, upon the issue in controversy, will normally carry little weight, for it cannot be tested by cross-examination nor independently appraised, and the parties have invoked the decision of a judicial tribunal and not an oracular pronouncement by an expert.

Although in modern practice (as in the present case), expert evidence is routinely appraised and cross-examined, the position essentially remains that an expert witness’s opinion is only a factor (albeit an important one) in the decision of a judge or jury.

It is abundantly clear therefore, and has been for many years in our courts, that an expert witness is not in the position to provide the court with a statement of unqualified conclusions about the question of fact on which his opinion bears. If he does so, the effect of his testimony may well be much diminished. In this context, it is perhaps worth noting that an expert witness is in a particularly privileged position in our courts. Prior to the decision, he is the only person permitted to express an opinion. Other witnesses must confine themselves to facts. Further, an expert witness will routinely rely on assumptions, hearsay evidence, his impression of testimony that he has not heard, and reports, statements and other secondary sources of information, all of which might be incompetent in a court of law if presented as factual evidence. It is therefore of the utmost importance that any expert witness carefully describes the source and assesses the worth of all material on which his opinion is based. We refer to the case of Gilmour v HM Advocate6 (paras 79, 80).

If the approach taken by the court is a paradigm warning to experts in relation to empirical fact lying within the province of the decision-maker, more recent guidance has been given reiterating the court’s duty to make findings as opposed to simply adopting an expert’s views. In Kennedy v Cordia (Services) LLP7 Lord Brodie considered the admissibility of expert evidence in a personal injuries action arising out of the pursuer’s fall in icy conditions:8

In the present case the dispute that had to be resolved was whether, on the basis of the essentially uncontroversial primary facts, as a matter of law, the reclaimers [the defender employers] were under a duty to take a particular precaution (providing attachments to footwear and ensuring their use) and, had they taken that precaution, whether the respondent would have suffered injury. That was something that the Lord Ordinary was fully equipped to do without any instruction or advice; it was squarely within his province as judicial decision-maker. No additional expertise was required. It may be that a judge has personally never carried out a risk assessment of any kind. That does not mean that, having heard evidence of the nature of the activity being assessed and having been provided with a document recording the risk assessment, he cannot determine whether or not the assessment was “suitable and sufficient” in terms of regulation 3(1) of the [Management of Health and Safety at Work Regulations 1999]. It is the job of a judge to hear evidence about matters with which he may previously have been totally unfamiliar and, on the basis of that evidence, come to conclusions of fact and then apply the relevant law to these facts. In Midland Bank Trust Company Limited v Hett Stubbs & Kemp [1979] 1 Ch 384 (a case of alleged negligence on the part of a solicitor engaged to carry out a conveyancing transaction) Oliver J was faced with a similar situation to that which faced the Lord Ordinary here. In what has become a much-quoted passage, he said this, at p. 402:

‘I must say that I doubt the value, or even the admissibility, of this sort of evidence, which seems to be becoming customary in cases of this type. The extent of the legal duty in any given situation must, I think, be a question of law for the Court. Clearly if there is some practice in a particular profession, some accepted standard of conduct which is laid down by a professional institute or sanctioned by common usage, evidence of that can and ought to be received. But evidence which really amounts to no more than an expression of opinion by a particular practitioner of what he thinks that he would have done had he been placed, hypothetically and without the benefit of hindsight, in the position of the Defendants, is of little assistance to the Court whilst evidence of the witness’s view of what, as a matter of law, the solicitor’s duty was in the particular circumstances of the case is, I should have thought, inadmissible, for that is the very question which it is the Court’s function to decide’.

C. The Realities of Modern Practice

Bearing in mind the foregoing admonitions, what then is the role of the expert in professional negligence litigation? Perhaps, notwithstanding the quantity of judicial ink addressing the issue, the reality is rather more prosaic. Each of the cases mentioned above in reality identifies the professional obligations incumbent upon experts. They do not, and are not intended to, discuss the pragmatic and practical aspects of the role. Moreover, as society has become more complex and more aspects of business and private life are thought to lie within the province of one profession or another, the need for expert opinion where things are perceived to have “gone wrong” has increased exponentially. Indeed, it is not unreasonable to suggest that in a developed, economically active society there shall be an increasing need for the advice of those who engage in the wide variety of professional activities now commonly encountered. The historical categorisation of “professions” and “trades” is probably an anachronism which fails to address the societal changes wrought by demographic, scientific and clinical advances over the last two centuries. Why might a computer programmer not be asked to explain her decision to write a particular line of code which thereby exposed the computer user to an increased threat from an obscure but identified virus? If the decision was a consequence of a judgement weighing the risks, advantages and disadvantages of such a piece of code, is such not a matter for expert analysis? Of course, such an example demonstrates the need not for one role for the expert witness but rather a multiplicity of roles arising in relation to such a scenario.

Experience suggests that there are at least four and possibly five distinct roles which the expert might be called upon to perform in the context of dispute resolution/litigation. Plainly, much will depend upon the nature of the expertise under scrutiny. In addition, especially within the context of claims against those who have professional indemnity insurance, the professional under challenge will, more often than not, have the benefit of experienced insurers and solicitors. As a corollary, those who feel aggrieved may well require to instruct solicitors who are less familiar with either the profession or professional branch concerned or the constraints of litigation in such a context.

(1) The investigator

If the issue truly arises out of the carrying out of some professional skill or art the detail of which is a mystery to those unskilled in such it must be axiomatic that some investigation will be likely. Obviously, in many cases the basic facts will have been fully explored by the legal teams involved. For example, the allegedly negligent conveyancer’s file will have been recovered and pored over. The client’s precognition will have addressed the solicitor’s mandate. The lender’s terms of engagement will have been considered.

In reality, the expert will frequently identify issues which require to be investigated before any concluded view might be taken in relation to breach of duty. Examples might be found of cases where a solicitor’s knowledge of his client’s intentions in relation to development of a property may or may not be relevant where a material period of time has elapsed during which the possibility of development could reasonably be discounted as a matter to be drawn to the attention of potential lenders.9 Such knowledge may or may not be apparent to the solicitors instructed but might reasonably be anticipated to be the sort of issue which an expert might, in an appropriate case, bring to the client’s and his solicitor’s attention.

Likewise, it is not uncommon where losses are sought to be recovered in relation to claims arising out of events many years previously for experts to suggest avenues of attack or defence where law or practice has in the meantime changed. Examples can be found in the field of conveyancing relating to letters of obligation, the necessity for site visits and the requisites for a competent and sufficiently comprehensive report on title. Practice in relation to each of these aspects of day-to-day conveyancing has drastically altered over the last ten years. Diverging views in relation for example to standard forms of clauses in missives has resulted in the need for creation of organisations such as the Standard Missives Joint Working Party of the Edinburgh Conveyancers’ Forum. An expert relying on what is perceived to be a standard clause in modern practice would in all likelihood be providing a pretty poor opinion if he or she were to suggest that the Working Party’s suggestions are indicative of practice in earlier years.

It also ought to be borne in mind that experts may be engaged not only in relation to whether or not there has been negligence/breach of duty but whether any admitted breach has been causative of loss. In many cases, the quantum of damages will necessarily demand investigation by experts. The input of the forensic accountant exemplifies the role of expert/investigator. Invariably, such an expert will be provided with basic documentation in relation to the performance of individuals or companies. In the real world however such experts frequently advise on the recovery of documents the existence of which is beyond the ken of mere lawyers.

For the avoidance of doubt, it is not suggested that the investigator expert don a forensic trenchcoat and fedora. Indeed, it is no part of the expert’s function to effectively dig about to find material which might support his side’s position. Such would, having regard to the dicta mentioned above, be anathema. The instructing solicitor must do all within his power to carry through such investigations as the expert identifies. Plainly, steps should already have been taken to ensure that the information initially provided to the expert is as complete as possible. The investigator expert does however require to address the issues in the case and in so doing must take steps to ensure that his opinion satisfies the proper requirements of the court in relation to a presentation of the whole factual matrix necessary for the just determination of the cause.

(2) The gatekeeper

The role of the expert as gatekeeper remains to some extent unrecognised. However, the importance of this role cannot, it is submitted, be underestimated.

Claims of professional negligence have diverse consequences. In the first place, the professional reputation of individuals is invariably placed in the public domain for dissection. In the second place, the ability of individuals to earn a living may well be adversely affected. In the third place, the costs of professional practice may substantially increase in consequence of claims or a claims history. The consequences for individuals and firms can be dire.

It is the first consequence that more often than not has greatest impact on people. Professional men and women often consider the making of a claim against them as a personal attack. He or she might often think of such a claim as being a challenge to his or her raison d’être. The emotional consequences might outweigh even a significant pecuniary disadvantage. It follows that such claims ought not ordinarily to be advanced unless they have some proper foundation.

It has been recognised in Scotland for many years that the proper conduct of professional negligence litigation demands that no such claim be advanced before the court unless there is available to the pursuer and his advisers suitably qualified expert opinion that supports the existence of certain professional practices or duties and that same have been breached to the pursuer’s detriment. The point has been made forcefully in a number of decisions relating to vexatious litigants. In Lord Advocate v McNamara10 the opinion of the court was delivered by Lord Reed. He made the following remarks in relation to the advancing of claims against professionals in the absence of appropriate opinion evidence:11

As we have explained, these proceedings were based on allegations of professional negligence which were unsupported by the opinion of anyone qualified to express an opinion on that issue. It is not suggested that they were instituted in the expectation that such support could be obtained; nor does there appear to have been any attempt to obtain such support. In those circumstances, we consider that we are entitled to conclude that the proceedings were instituted without any reasonable ground and were vexatious.

More recently, Lord Woolman had cause to discuss the requirements for an expert witness to support a claim in relation to a counter-claim arising out of alleged professional negligence in the related case of Tods Murray WS v Arakin.12 He stated:13

The pursuers emphasised the vital importance of a party being in possession of an appropriate expert before making allegations of professional negligence. They contended that in the absence of such a report, it is an abuse of process to institute and persist in such proceedings.

In response, Mr McNamara argued that in respect of some of the allegations, no expert was required. This was most clearly put in the defenders’ Note of Argument, which stated “sometimes matters of misconduct are just so blatant they require no experts’ view to demonstrate that this is the case.”

I reject that approach. In my view, allegations of professional negligence require to have a proper foundation. Without such underpinning, the court is not in a position to make a finding in favour of the defenders (Walkers Evidence, third edition para. 16.3). As a solicitor must always exercise a measure of judgement in fulfilling his duties, it is not enough to say that he has failed to implement his instructions. The allegation must always be buttressed by a report from an appropriate witness, which states that the course taken was one that no solicitor exercising ordinary skill and care would have taken.

In the absence of such a rule, it would be open to a party to make whatever assertions he or she chose, however spurious or mistaken. In my view, that is just what has happened here.

Lest it be thought that the rules in Scotland in relation to the stringency inherent in requiring the production of an expert report are to any extent inconsistent with Midland Bank Trust Company Limited,14 it should be noticed that in England and Wales a not dissimilar approach in relation to the need for expert support is adopted in modern practice.15 However, for completeness’ sake, it should be noticed that an exception is made in that jurisdiction in relation to some claims arising out of negligent conveyancing16 although same is probably explicable by reference to technical differences in conveyancing practice.

The requirement for an expert report supporting a claim necessarily creates the role of gatekeeper expert. It probably goes without saying that those with a sceptical approach might consider that the necessity for such a role to be borne in mind by the expert witness is indicative of protectionism or cronyism. On the other hand, it is submitted that the views provided by both Lord Reed and by Lord Woolman amply demonstrate the necessity of such a role if the court is to exercise its jurisdiction equitably and efficiently.

(3) The mediator

Within the context of disputes relating to professional liability it is, by the nature of things, by no means unusual for experts also to be engaged in mediation practice. However, the individuals concerned will be at pains to recognise the very distinctive role of the mediator in a mediation process from other aspects of their professional practices including the provision of expert opinion.

It is perhaps interesting to observe that the overlap in areas of expertise between mediators and expert witnesses is sometimes thought to be a necessary subject for analysis.17

For present purposes the mediator expert remains principally a witness. What has changed in the course of the last 20 years is an increasing reliance by the court upon experts to reduce the scope of dispute. In particular, since the introduction to the Court of Session of commercial actions the court has made demands upon parties to narrow the scope of any controversy and, where appropriate, to demonstrate that steps have been taken towards agreeing evidence.

Rule 47.12 of the Rules of the Court of Session 1994 makes provision for Procedural Hearings in commercial causes. Rule 47.12(2)(h) provides that the court may direct:

that skilled persons should meet with a view to reaching agreement and identifying areas of disagreement, and may order them thereafter to produce a joint note, to be lodged in process by one of the parties, identifying areas of agreement and disagreement, and the basis of any disagreement.

Needless to say, in many professional negligence claims there will be substantial areas of agreement. However, inasmuch as such disputes not infrequently require to be resolved by reference to the exercise of a professional judgement there will always remain scope for disagreement. This rule nonetheless requires a meeting. Such meetings will, no doubt, be approached in a positive fashion. Experience suggests that such meetings effectively operate as a form of informal mediation. That may well be desirable.

An understandable desire to reduce the scope of disagreement is bolstered somewhat by the provisions of Rule 47.12(2)(i) which provides that the court:

may appoint an expert to examine, on behalf of the court, any reports of skilled persons or other evidence submitted and to report to the court.

The position in the Sheriff Court is arguably even more demanding in as much as rule 40.12(3)(m) of the Ordinary Cause Rules 1993 empowers the sheriff to make any order which the sheriff thinks “will result in a speedy resolution” of the case!

What ought to be borne in mind by expert witnesses is that they cannot indulge in advocacy. To do so would plainly run counter to the whole ethos of the expert witness.

Mention was made above of the significance of professional judgement on the part of those whose actions are being criticised. Inasmuch as professional judgement necessarily connotes the possibility of a range of different actions/advice on the part of the individual concerned it must at least be possible for expert witnesses to effectively mediate in a way which reduces the breadth of the professional judgement challenged. Such a form of “mediation” has the significant advantage of narrowing the issues in dispute to the point where, if appropriate, certain evidence might be agreed or, where possible, compromise arrived at.

A necessary caveat must be stated. It is no part of the expert witness role to indulge in negotiation. She cannot enjoy any such mandate. More importantly, notwithstanding the professional obligations upon the expert to assist the court as outlined above, any such expert will nonetheless still require to answer to his client. There will be occasions where the expert witness risks professional embarrassment by failing to observe the limits imposed upon her to confine opinions advanced to the four walls of the litigation concerned and the factual matrix under consideration.

(4) The quantifier

When discussing the role of expert witnesses in professional negligence cases it is inevitable that the focus will be on the merits of the claim. In reality, many litigations focus as much upon the question of causation and the quantum of damages as upon primary liability.

The quantifier expert will be required to opine on the pursuer’s position but for the negligence/breach of duty complained of. In many cases, as suggested earlier, the nature of the breach of duty dictates that the quantifier expert shall be one and the same person who speaks to the merits. That will not always be the case. Frequently, within the context for example of clinical negligence claims, a number of areas of expertise arise for consideration. The birth of a baby born with cerebral palsy may well focus upon the action or inaction of an obstetrician. The prognosis for the child, damaged and undamaged, will be addressed by others such as neonatal paediatricians and paediatric neurologists.

Lest it be thought that the quantifier expert’s role is in some way lesser than that of those providing opinions on the merits of a claim, the position in the real world is far more demanding. It is frequently the case that at the point in time at which the disgruntled client asserts that the professional’s negligence occurred many alternative ways forward might have been in contemplation. It is certainly not uncommon for example for developers of land to consider a number of different possibilities for development when acquiring a site. An error in relation to the extent of the title obtained may require the consideration of a series of different hypotheses as to how the land would otherwise have been developed. For example, planning considerations may have impacted upon the number of plots which might have been marketed. Such might plainly have impacted upon the profit to be generated by the development. Equally, planning conditions may have rendered an otherwise profitable part of a developer’s land bank of no worth whatsoever.

Indeed, in certain respects the quantifier expert’s function is particularly difficult. The discussion above in relation to the development value of land is an obvious example. The developer will invariably suggest that he would have adopted whatever scheme would have maximised the profit to be generated. The obligation on the expert however will necessarily require him to test that proposition. To fail to do so would be a dereliction of his obligations to the court as well as to his client. But in fulfilling his obligations he will necessarily risk being perceived as taking views adverse to those of his client. Moreover, the quantifier expert will almost invariably also be an investigator expert. It is not always the position that the client assists in providing information which might have a consequence of reducing the value of the claim being advanced. Of course, the preceding observations arise within the context of the expert witness retained on behalf of the claimant. Similar considerations will arise nonetheless for those instructed and retained in respect of the defence of such claims.

Another complicating factor for the quantifier expert arises from the need to consider the quite distinct issue of mitigation of damages. It is trite to observe that the onus of proof in relation to a failure to mitigate damages rests upon the defender. Although issues in relation to mitigation might have been identified by defenders in appropriate cases it will frequently be the quantifier expert who is charged with forming a view on the steps which might properly have been taken by the claimant when presented with the breach of duty hypothetically conceded to have taken place.

(5) The communicator

It is implicit throughout the foregoing that expert witnesses are reasonably anticipated to be well-respected, vastly experienced and of obvious integrity. All of those attributes however are, within the confines of dispute resolution, almost valueless in the absence of an ability to relay complex factual material, explain sometimes ethereal concepts and address all manner of hypotheses which might be advanced in discussion with the decision-maker.

Of particular worth in the expert witness is a demeanour which is empathetic to the role of the decision-maker. Equally, he or she should be capable of communication in a fashion which is neither arrogant nor submissive.

D. The Choice of an Expert Witness in the Real World

It will be apparent that the demands made upon expert witnesses are many and varied. The scepticism which is sometimes applied to expert evidence is, for the most part, balanced by the need to repose confidence in those witnesses skilled in the multiplicity of professional roles found in modern society.

This discussion is intended to broaden issues surrounding the instruction of expert witnesses in professional negligence claims. It highlights the diverse skill set which ought to be found in the well instructed expert’s toolbox. It may assist experts in recognising the different roles that they perform at a subconscious level.

Inevitably, professional negligence litigation is testing of all those involved in whatever role and at whatever level. What is most important is that such litigations are conducted in a way which reflects the nature of the issue at hand. Professionalism, propriety, integrity and diligence require to be deployed throughout.

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