An Introduction To Expert Evidence Professional Witnesses – Avoiding the Smoke and Mirrors

Expert witnesses have an important role to play in litigation when scientific, technical, medical, accounting or other specialised knowledge may be required to assist the court in determining the matters in issue.

Essentially, expert evidence is opinion evidence provided by a suitably qualified specialist. Having identified the reason why such an opinion is required that should, in turn, point to the qualifications, experience or skills that are necessary to proffer such an opinion in an admissible form. It is important to remember that not everyone who claims to be an expert, is indeed an expert.

Preparing and adducing such evidence can be a very expensive exercise thus consideration has to be given at the outset of any litigation, by way of a cost/benefit analysis, as to the utility and need for such evidence. If expert evidence is to be adduced it must be effective, persuasive and useful – otherwise it can be an expensive missed opportunity!

To the extent that there is any doubt as to whether a single expert or multiple experts may be required to proffer the required evidence, that matter has to be considered, interrogated and explored in the process when seeking to arrive at a suitable case concept, and then tested in the process of commissioning each expert. Building a mosaic of expert evidence with multiple expert witnesses is a difficult forensic task and, if necessary, has to be undertaken carefully and in a structured and measured fashion.

The value of such evidence depends upon “the authority, experience and qualifications of the expert and above all upon the extent to which his … [or her] … evidence carries conviction”.2 (Davie v The Lord Provost, Magistrates and Councillors of the City of Edinburgh (1953) SC 34 (‘Davie’) per Lord President Cooper at 39-40 – cited with approval by Heydon JA at [59] in Makita (Aust) Pty Ltd v Sprowles (2001) 52 NSWLR 705) Thus whilst there are fundamental technical requirements, i.e. that the chosen witness have the relevant qualifications, expertise or skills to give the required opinion, there are also practical considerations as to the quality of evidence that the witness can give. Here “quality” is used to refer to how that expert will perform as a witness. For example, can the witness explain technical concepts simply, is he or she able to communicate the reasoning used and fluently identify the facts upon which his or her opinion is based, can the witness deal with cross-examination, and do they come across as credible experts in his or her field? Proofing expert witnesses is essential so that the practical value of their opinion can be thoroughly explored.

A successful expert witness is one whose opinion is accepted by the decision-maker and influences and impacts upon the outcome of the litigation. He or she has to be more than merely qualified as an expert they have to present, communicate and engage as an expert. The most qualified, intelligent and well-organised witness will fail in this regard if the evidence they give is ambiguous, poorly reported, buried in professional jargon, inflexible or lacking in confidence or fluency.

If an expert has not previously appeared before the relevant judge, the expert’s first report introduces the witness to the court. Even if the expert has previously been heard by the judge it is important that the expert’s written work continue to reinforce the proposition that he or she is an expert and able to communicate clearly and usefully in writing.

Some obvious examples that will encourage the court to doubt a witness’ capacity as an expert when receiving his or her report include amongst many others, where the expert is not qualified to give the opinion by clearly trespassing outside their declared expertise, evident internal inconsistencies, a report that obfuscates the basis for conclusions, the use of unnecessary professional jargon, dense and impenetrable formatting, a lack of headings or paragraph and page numbers and compendious attachments. The expert needs to empathise with the needs of a busy judge, those needs differ depending of the nature of litigation, opinion evidence tends to be more common in complicated litigation. The witness needs to present as an expert which requires lucid reporting. Forcing a judge to trawl through reports seeking to identify relevant opinions, and the basis for them, is unlikely to be persuasive and depending on the judge to work it out makes the client a “hostage to fortune”.

The expert needs to be independent to make his or her opinion useful to a court, a partisan expert is of little, or no, assistance.

An obvious example of an expert whose independence may become an issue is an expert who gives evidence repeatedly for a particular client or group of clients with a singular interest.3 (Vita Health Laboratories Pty Ltd v Pang Seng Meng [2004] 4 SLR 162 at [81]) Indeed there is a widespread view that one can readily obtain any expert evidence that is needed to establish the client’s position. In that regard Judge Posner in Stoleson v United States of America said “… there is not much difficulty in finding a medical expert witness to testify to virtually any theory of medical causation short of the fantastic”,4 (Stoleson v United States of America 708 F 2d 1217 at 1222 (7th Cir 1983) and added to that some years later with, “The professional expert witness who testifies with scant regard for the truth is an old problem in tort as in other areas of litigation.”5 (Albers v Church of the Nazarene 698 F 2d 852 at 858 (7th Cir 1983); see J Langbein (1985) 52 Uni of Chi LR 823 at 835)

Similarly Arthur C Clarke quipped:

For every expert, there is an equal and opposite expert.

These perceptions of expert evidence tend to negate its utility and some effort should be made to highlight and emphasise the independence of one’s chosen expert. That may require some care in choosing the appropriate professional to give evidence on behalf of your client. The more engaged and targeted expert evidence the more likely a court will find it useful.

The capacity of an expert witness to perform is a critical consideration but how does one make a judgment in this regard prior to engaging an expert? There may be little information regarding the capacity of an expert to perform as a witness either because such information is unavailable or the expert has yet to appear as an expert witness, or has done so only sporadically.

There are a number of sources which may provide information as to a prospective expert witness’ capacity in this regard, previous evaluation of the his or her evidence in earlier cases which appear in court judgments, a track record of appearing for clients where the client’s case has succeeded, recommendations by colleagues, one’s own previous experience using the witness or a demonstrable history outside courts of a capacity to communicate clearly both orally and in writing.

If one is able to identify a good expert witness then that can be “gold” in the right case, and building a portfolio of such witnesses can assist solicitors and counsel when preparing matters for trial.

The quality and parameters of available expert evidence can have a primary impact on a successful case theory and is, therefore, of fundamental importance. In other words that evidence needs to be obtained early in the litigation process, and for a plaintiff as part of the preparation of a case for trial. Belated attempts to gather such evidence usually appear to the court as an after-thought, and coming later in the process may present technical issues around the need to amend pleadings or more existential questions as to the merits of the litigation.

It is important to remember that whatever expert opinion might be adduced it is for the court not the expert to determine the outcome of the case.

Expert witnesses, however skilled or eminent, can give no more than evidence. They cannot usurp the functions of the jury or Judge … any more than a technical assessor can substitute his advice for the judgment of the Court … Their duty is to furnish the Judge or jury with the necessary 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.6 (Davie, per Lord President Cooper at 39-40)

As talented as some experts are, or as many experts believe themselves to be, they should recognise and respect the role of the decision-maker in a court and avoid patronising or lecturing a court, and answer any question put carefully. This may require some careful proofing of a professional witness and assisting such a witness to recognise the nature of their role.

There are established court guidelines for experts and prospective witnesses should be encouraged to read and appreciate both the guidelines themselves and their rationale.7 (Federal Court of Australia ’s Expert Evidence Practice Note (GPN-EXPT) 25 October 2016, including the Harmonised Expert Witness Code of Conduct and the Concurrent Expert Evidence Guidelines) Relevant guidelines should be included when instructing prospective expert witness. Ascertaining whether such a prospective witness has actually read and understood those guidelines is of some importance, it will be readily apparent from any draft report. Where there are obvious difficulties in the form or content of a draft report the expert made need to review the guidelines.

2. The Nature of Expert Evidence

2.1 The Factual Foundation
It is always important to remember that an expert’s opinion is only as useful as the admissible evidence (facts) upon which it is based. There is no utility in an expert opinion that is not based on facts that have not been, or cannot be, proven. In that regard it is critical to ensure that when facts are required to be separately proved to provide part of the foundation of the expert opinion, that those called to give evidence to establish those facts can give such evidence in an admissible form.

The classical example is medical evidence of a patient’s condition or diagnosis where a doctor forms a medical opinion (in their field) after taking an oral history from, and examining, the patient. Typically, the doctor will take a contemporaneous note of the history and the outcome of his or her examination, which may include observations, diagnostic testing and vital signs. Such a medical opinion will rest on a combination of the history given by the patient and the examination made by the doctor. To the extent that the medical opinion rests on the patient’s history (as related by the patient to the doctor) the doctor can give no evidence as to the truth of what the patient has told him. Those facts have to be separately established by additional admissible evidence (i.e. other than evidence from the doctor).

The High Court held, in Ramsay v Watson,8 (Ramsay v Watson (1961) 108 CLR 642) that “When a physician’s diagnosis or opinion concerning his patient’s health or illness is receivable, he is ordinarily allowed to state the ‘history’ he got from the patient”,9 (Ramsay v Watson, per coram at 648) but “If the man whom the physician examined refuses to confirm in the witness box what he said in the consulting room, then the physician’s opinion may have little or no value, for part of the basis for it has gone”.10 (Ramsay v Watson, per coram at 649) It is, therefore, very important that expert witnesses are asked to opine on the basis of facts that can (and will) be established by admissible evidence. That is a matter that must be considered before any letter of instruction to an expert is settled. Indeed the process of identifying those facts and why the expert’s opinion is required allows counsel or an instructor to interrogate and review the client’s case theory.

2.2 The Instruction
What element (or elements) of the client’s case requires the expert opinion? It is the nature of that element (or elements) which explains what the client needs to obtain from the expert.

The letter of instruction to an expert is a very important communication it is discoverable and both the court and the other parties are entitled to see it. In criminal matters the prosecution will disclose such letters in respect of expert evidence that the crown seeks to lead. As Justice Warren stated:

As a fundamental principle, when a witness is called in order to provide expert opinion evidence all of the facts and instructions upon which that witness bases the expert opinion are admissible and subject to production11 (Cobram Laundry Services Pty Ltd v Murray Goulburn Co-operative Co Ltd [2000] VSC 353 at [58]; see also Automasters Australia Pty Ltd v Bruness Pty Ltd [2004] WASCA 229 per Steytler J, Makita (Aust) Pty Ltd v Sprowles (2001) 52 NSWLR 705, and Pownall v Conlan Management Pty Ltd (1995) 12 WAR 370)

At a hearing a letter of instruction may, ultimately, be used as the basis for cross-examination of your client’s expert. Thus settling such an instruction requires a clear, current and engaged understanding of the purpose of the evidence sought and the rules which apply to the admissibility of expert opinion. Seeking to obtain evidence that is inadmissible, or of limited utility, is obviously pointless and wastes the client’s resources.

A party seeking to adduce an expert opinion should not be taken by surprise. An expert should be able to identify all the factual matters relied upon in the process of examination in chief, thus avoiding the risk of any surprises in cross examination. If the facts upon which the expert has relied cannot be identified then the expert opinion may well be inadmissible.

One of the important functions of a letter of instruction is to communicate to the expert the facts and/or assumptions that the expert is to take into account in rendering his or her opinion. The expert can then, when cross examined as to what he or she has relied upon, identify those matters with particularity. Experts should be dissuaded from excursions of their own, or relying on generalised factual propositions, that is unless additional technical work by the expert is necessary to support his or her opinion. If the expert has relied upon matters that were not included in the letter of instruction, then they need to identify those facts and the source of those facts with particularity and explain why they have done so. Indeed it is been observed that (emphases added):12 (Trade Practices Commission v Arnotts Ltd (No 5) (1990) 21 FCR 324 per Beaumont J at 330)

In complicated litigation, there are sound reasons of policy which support a rule that the premises considered by the expert should be expressly stated rather than left to speculation. It is preferable that these matters be clarified when the witness is examined in chief rather than leave room for argument later as to exactly what matters the expert had in his mind when expressing his conclusions.”

If a letter of instruction is unclear, ambiguous or poorly composed any expert opinion provided in response is likely to share the same qualities. A complicated piece of litigation can turn on the efficacy and admissibility of expert opinion. If a lawyer is called upon to draft such a letter and lacks experience then they should seek assistance from colleagues and, if necessary, seek some further training in this area.

Where an objection is taken to the admissibility of an expert opinion during trial on the basis that the facts upon which the opinion is based have not been established by admissible evidence then that objection needs to be dealt with when the objection is taken and not deferred until the conclusion of the trial because “of its capacity to distort the trial process. There is a real danger … that a failure to rule on the admissibility at the time of tender will cause unfairness to one or other of the parties”.13 (Professional Services (Aust) Pty Ltd v Computer Accounting and Tax Pty Ltd (No 2) (2010) 261 ALR 179 per Martin CJ at 200 ([96]) Of course, in administrative tribunals which are not strictly governed by the rules of evidence such objections need to be couched in terms that reflects the nature of the prospective unfairness rather than the strict enforcement of evidential rules.

2.3 The Opinion
Any opinion proffered to a court must be admissible. We start with the nature of the expertise required to proffer the opinion and how that expertise is to be described, and the nature of the opinion sought.

In Makita Heydon J observed,14 (Makita at [85])

“… it must be agreed or demonstrated that there is a field of ‘specialised knowledge’; there must be an identified aspect of that field in which the witness demonstrates that by reason of specified training, study or experience, the witness has become an expert; the opinion proffered must be ‘wholly or substantially based on the witness’s expert knowledge’; so far as the opinion is based on facts ‘observed’ by the expert, they must be identified and admissibly proved by the expert, and so far as the opinion is based on ‘assumed’ or ‘accepted’ facts, they must be identified and proved in some other way; it must be established that the facts on which the opinion is based form a proper foundation for it; and the opinion of an expert requires demonstration or examination of the scientific or other intellectual basis of the conclusions reached: that is, the expert’s evidence must explain how the field of ‘specialised knowledge’ in which the witness is expert by reason of ‘training, study or experience’, and on which the opinion is ‘wholly or substantially based’, applies to the facts assumed or observed so as to produce the opinion propounded. If all these matters are not made explicit, it is not possible to be sure whether the opinion is based wholly or substantially on the expert’s specialised knowledge.”

It is immediately clear that an expert should not form a theory or conjecture about a subject without firm evidence, nor should an expert be encouraged to speculate. Arguments along the line that if there’s smoke there must be fire have no utility in a court. If there are correlations between facts and certain outcomes the mechanism by which such facts may give rise to the outcome have to be explored and the line of reasoning exposed and evaluated. If the Court, or finder of fact, considers that an expert is merely speculating then that may destroy the party’s case that the expert has been called to support. The nature of the reasoning process that is set out in an expert’s report has to be logical and rational if it is to be accepted.

Thus, second-hand views or expressed opinions beyond the expert’s field will be damaging and inadmissible. Many experts are unfamiliar with the rules of evidence with limited experience as a witness and use a more relaxed style of communication, sometimes this requires an expert to make an adjustment so that any report is largely in an admissible form.

Often “chest beating” experts those determined prior to trial to be evangelical proponents of their opinions are the first to concede in the process of cross examination. Inflexible and obdurate experts who are unable to understand or respond to questions regarding their opinions are unlikely to be persuasive. Expert evidence needs to be rigorously tested in proofing. However, it must always be remembered that it is the expert’s opinion that is adduced not that of the instructing solicitor or counsel.15 (See section 3.1)

Not only are there risks to the admissibility of the expensive evidence obtained for the client; but inadmissible or poorly drafted or delivered expert evidence may buttress the credit of the other side’s witnesses. That can extend both to the other side’s experts and, on occasion, lay witnesses.

The lawyer instructing an expert should never assume that the expert understands the rules that apply to admissibility or that they have clearly understood guidelines16 (Such as the Federal Court of Australia’s Expert Evidence Practice Note (GPN-EXPT) 25 October 2016, including the Harmonised Expert Witness Code of Conduct and the Concurrent Expert Evidence Guidelines) published to aid experts in the process of producing reports and giving evidence. Often they do not. Equally, the pressure of giving expert evidence in a court should never be underestimated.

3. Adducing Expert Evidence

3.1 Preparing An Expert Witness
Legal practitioners must not “coach” a witness, whether an expert or lay witness. In the Legal Profession Uniform Law Australian Solicitors’ Conduct Rules 2015 rule 24 considers how to preserve the integrity of evidence:

24. Integrity of evidence — influencing evidence

24.1 A solicitor must not —
24.1.1 advise or suggest to a witness that false or misleading evidence should be given nor condone another person doing so, or
24.1.2 coach a witness by advising what answers the witness should give to questions which might be asked.

24.2 A solicitor will not have breached Rules 24.1 by —
24.2.1 expressing a general admonition to tell the truth,
24.2.2 questioning and testing in conference the version of evidence to be given by a prospective witness, or
24.2.3 drawing the witness’s attention to inconsistencies or other difficulties with the evidence, but the solicitor must not encourage the witness to give evidence different from the evidence which the witness believes to be true.

Similar rules apply to barristers, see Legal Profession Uniform Conduct (Barristers) Rules 2015 at rules 69 and 70. In R v Momodou, Judge LJ, in delivering the judgment of the Court of Appeal of England and Wales,17 (R v Momodou [2005] 2 All ER 571; [2005] 1 WLR 3442; passage cited with approval in the WA Court of Appeal in Majinski v State of Western Australia (2013) 226 A Crim R 552; [2013] WASCA 10 per Martin CJ at [29] ) said:

There is a dramatic distinction between witness training or coaching, and witness familiarisation. Training or coaching for witnesses in criminal proceedings (whether for prosecution or defence) is not permitted. This is the logical consequence of the well-known principle that discussions between witnesses should not take place, and that the statements and proofs of one witness should not be disclosed to any other witness: see R v Richardson [1971] 2 QB 484; R v Arif The Times, 22 June 1993, R v Skinner (1993) 99 Cr App R 212 and R v Shaw [2002] EWCA Crim 3004. The witness should give his or her own evidence, so far as practicable uninfluenced by what anyone else has said, whether in formal discussions or informal conversations. The rule reduces, indeed hopefully avoids, any possibility that one witness may tailor his evidence in the light of what anyone else said, and equally, avoids any unfounded perception that he may have done so [61].

In Re Equiticorp Finance Ltd; Ex parte Brock,18 (Re Equiticorp Finance Ltd; Ex parte Brock (No 2) (1992) 27 NSWLR 391 per Young J at 395) Young J noted that:

“It is clear that a witness might confer with his or her solicitor or counsel, or the solicitor or counsel for the party calling the witness, and that during such conference the solicitor or counsel concerned may give the witness advice. That advice may certainly include:

(1). advice that the witness should refresh his or her memory from contemporaneous documents;

(2). directing the witness’ mind to the point about which questions may be asked;

(3). giving the witness a sketch of court procedure;

(4). directing the witness’ attention to points in his or her evidence which appear to be contradictory or fantastic;

(5). reminding the witness to bring to court all relevant documents;

(6). advising the witness as to the manner of answering questions (for example, “In cross-examination listen to the question, just answer the question asked with as concise an answer as possible”); and

(7). giving advice as to appropriate dress and grooming.

There may be other permitted areas.”

When proofing an expert witness counsel must ask the expert to explain their written opinion(s). That gives a clear indication of how the witness is likely to give his or her evidence. As Young J points out that can include identifying points about which questions may be asked and posing those questions to the expert to see how the expert is likely to perform.

The point of the prescription against “coaching” is that the expert witness give “his or her own evidence, so far as practicable uninfluenced by what anyone else has said”.19 (See Judge LJ in the passage from R v Momodou above) It has to be given in an admissible form and that may involve explaining to the expert witness relevant court rules and procedures. Care has to be taken by lawyers to avoid suggesting answers to a witness or otherwise influencing the evidence of the witness. A solicitor or counsel should not advise a witness as to how to answer a question.

Good expert evidence comes from an expert who is well versed in their subject without being arrogant or patronising and has a facility for explaining complicated ideas simply. They should be open-handed and patently honest, even to the extent of admitting fallibility or the possibility of error. In respect of the latter they should do so only when necessary, and there is a primary difference between possible error and the limits of science in a particular field. A relevant and positive track record in his or her discipline, especially in similar matters makes a prospective expert witness ideal. No doubt that is why it has been suggested that in some situations, a brief discussion with a witness of his proposed evidence to clarify some point of ambiguity or uncertainty may be desirable in promoting the integrity and accuracy of the trial process.20 (HKSAR v Tse Tat Fung [2010] HKCA 156; [2010] HKEC 815 at [73])

The expert’s mastery of their subject must be both practical and theoretical. An expert is often asked to deal with hypotheticals and being able to do so under cross examination in a way that emphasises the expert’s written reports is a real skill, and one that is truly rare. The ability to deal with hypotheticals also allows the practiced expert to effortlessly, and positively, locate their testimony amongst that of other experts in a credible, fluent and convincing fashion.

3.2 Examination In Chief
The process of adducing expert evidence in chief is usually to briefly ask the expert about their qualifications, training and experience before putting his or her written reports to the expert and tendering those reports into evidence. This is the moment where there may need to be some tidying up of those reports before tender to clarify aspects of the reports that have been exchanged with the other parties. The process of exchanging export reports often includes both the original report of the expert and his or her responsive reports to those of other experts, the process is intended to be synthetic (i.e. proposition and counter proposition moving towards identifiable common ground).

In recent times a variety of devices have been developed to assist in that process, including: (i) a conference of experts with similar qualifications (generally without lawyers) where the experts are encouraged to explain their opinions to each other, identify common ground, record extraneous issues and then report back to the court or tribunal and a copy of that report is made available to the parties; (ii) on occasion the court may appoint a conference facilitator to assist the experts to explore common ground and identify outstanding issues within a conference of experts, and (iii) concurrent expert evidence by groups of similarly qualified experts given at the same time before a court or tribunal allowing it to synthesise the available evidence with all experts present (“hob-tubbing”).

The Federal Court’s Concurrent Expert Evidence Guidelines describe the use of concurrent evidence:

The use of concurrent evidence for the giving of expert evidence at hearings as a case management technique will be utilised by the Court in appropriate circumstances (see r 23.15 of the Federal Court Rules 2011 (Cth)). Not all cases will suit the process …”,21 (Concurrent Expert Evidence Guidelines [2])

and,

Parties should expect that, the Court will give careful consideration to whether concurrent evidence is appropriate in circumstances where there is more than one expert witness having the same expertise who is to give evidence on the same or related topics. Whether experts should give evidence concurrently is a matter for the Court, and will depend on the circumstances of each individual case, including the character of the proceeding, the nature of the expert evidence, and the views of the parties.22 (Concurrent Expert Evidence Guidelines [6])

If there are substantial areas of new evidence required from an expert witness then these should be in the form of supplementary reports or statements. Such additional evidence has to be exchanged with the other parties and if left too late may be excluded by a Court or tribunal. Early exchange of additional evidence is in everyone’s interest: the Court or tribunal and all the parties. Resolving the matters in issue with all the relevant evidence within the time set aside for the hearing is in the interests of justice. There is a tendency to permit the introduction of late expert evidence in the interests of fairness and that can create significant forensic issues when it occurs at the last moment – that is to be avoided.

3.3 Cross Examination
Other than seeking to determine whether a particular expert is an appropriately qualified expert to proffer the opinions he or she advances; cross-examination of an expert should involve identifying the expert opinions proffered, a careful elucidation of relevant facts and the bases upon which those expert opinions may have been formed (where necessary) and interrogating those opinions with a view to allowing the Court or tribunal to assess those opinions in the context any expert evidence led by your client and the matters in issue.

There are many different cross examination techniques.23 The cross examiner has to be careful not to entrench the opinion of the other party’s expert witness by merely encouraging the witness to repeat the evidence given in chief. Cross examination is carefully designed by experienced counsel to traverse those portions of the expert’s testimony that the advocate believes can be effectively challenged in aid of his or her client’s case. There are many bases upon which an expert opinion can be challenged including but not limited to (i) the facts or assumptions upon which the opinion is based, (ii) the logic of the reasoning giving rise to the opinion, (iii) whether there are additional matters or assumptions that the expert should have taken into account or made but did not, (iv) the relevance of facts or assumptions that the expert has relied upon, (v) further investigations that should have been made; (vi) whether the opinion of another expert is required to support a conclusion … etc.

Other than seeking to blunt the other side’s case by undermining the opinion offered by that party’s expert or experts, it may be necessary to put key propositions to the other side’s expert in cross examination. That is required where it is necessary to give the other side’s witness an opportunity to address aspects of your client’s case or any criticism that is to be made of that expert’s opinion in closing. Also you may seek to utilise the opportunity in cross examining an expert witness to obtain concessions that build your client’s case, or affirm facts or assumptions upon which your client’s expert evidence relies. If your questions in cross examination are not achieving one of these goals then it is possible that the line of questioning you have decided upon is ill-considered. Typically questions in cross examination are closed questions, i.e. where the cross examiner because of the exchanged expert evidence can readily anticipate the answer. Properly used this technique can have a narrative effect where the line of questioning tells its own story and highlights the points to be made in favour of your client’s case.

3.4 Re-Examination
This type of questioning comes at the end on an examination of your witness immediately after cross examination has concluded. At this stage you have led the witness’ evidence in chief, your opponent has cross examined and now you have the opportunity to deal with any matters that have been left hanging by the witness’ cross examination. For example, if the close question technique has been used in cross examination and your witness has not had an opportunity to get out important qualifications or explanations in providing an answer to key questions. Re-examination should focus on primary issues and be a relatively short process.

One has to be careful in cross examination that the manner in which questions are put and answered doesn’t leave an opportunity for your opponent to undo the impact of a cross examination of an expert witness by a short series of pithy questions in re-examination. That type of re-examination can be very effective if one doesn’t “over egg the pudding” by trying to achieve too much. Remember your witness has had the opportunity to give evidence both written and oral and has been cross examined, what you seek is a rebuttal of the key points of the other side’s case. If possible the order in which those questions are asked should seek to mirror the logical sequence which provides the architecture of your client’s case.

3.5 Re-calling Expert Witnesses
Generally a witness gets only one opportunity to give evidence. However, if the other side seeks to adduce evidence after your relevant expert has given evidence it may be necessary to seek leave to recall that expert to address any new evidential issues arising. That is something to keep in mind during the course of the evidence.

Conclusion

Expertise is by its nature siloed. Experts have limits and similar experts tend to share methods and outlooks because they have undergone similar education or training. It is counsel that needs to stitch the evidential tapestry against which the client’s case is to be measured. He or she should not be compartmentalised or artificially limited and his or her outlook must be driven by the legal parameters of the client’s case rather than the approach of others. Counsel needs to develop a working understanding and appreciation of relevant types of expert evidence in order to be able to assess it, to cross examine upon it and bring it to account in the client’s case. The variety of evidential matrices within which counsel is asked to work provides a stimulating environment in which one develops a working knowledge of many fields of endeavour, albeit usually only for the life of the litigation and until such knowledge gives way to the requirements of a new case. As Sir Arthur Conan Doyle observed through his character, Sherlock Holmes:

“I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.”

Arthur Conan Doyle, A Study in Scarlet

The Honourable Chief Justice Christopher Shanahan
The Supreme Court of Tasmania