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    HomeNews & ArticlesExpert Evidence: Key Cases, New Rules and New Realities

    Expert Evidence: Key Cases, New Rules and New Realities

    February 1, 2013  |  By:  Troy Lehman

    One of the basic rules of the law of evidence is that witnesses may not give opinion evidence.1   Expert evidence on subject areas beyond the fact-finder’s knowledge and experience is an exception to this exclusionary rule.

    In the 19th century there was considerable scepticism about expert evidence.2   Judges were concerned that juries might abdicate their decision making responsibilities to highly qualified experts. Expert bias was a concern for Judges more than a hundred years ago.3

    Trial judges have always been the gatekeepers when it comes to determining whether or not to admit expert evidence. However, as expert testimony became commonplace in Canadian courtrooms the gatekeepers became more relaxed in their views about its admissibility. Expert evidence was commonly admitted with frailties in the evidence (or the expert) going to weight rather than admissibility.

    Recent changes to the Rules of Civil Procedure and recent case law signals changing attitudes towards the use of expert evidence in civil proceedings. Expert evidence is being more closely scrutinized before it is admitted and relied upon.


    In R. v. Mohan the Supreme Court introduced a principled approach to the admissibility of expert evidence. Justice Sopinka indicated that for expert evidence to be admitted, the following criteria must be met:4

    (a)    It must be relevant;

    (b)    It must be necessary to assist the trier of fact;

    (c)    It must not offend and any exclusionary rule; and

    (d)    It must come from a properly qualified expert.

    The “relevance” criterion is a two part inquiry. The first part of the inquiry is simple:  Is the subject matter of the evidence logically relevant to the matters at issue?  This inquiry can be answered by the application of common sense.

    The second part of the inquiry involves a more complicated cost-benefit analysis. Justice Sopinka explains in his reasons in R. v. Mohan:5

     This further inquiry may be described as a cost benefit analysis, that is “whether its value is worth what it costs”…Cost in this context is not used in its traditional economic sense but rather in terms of its impact on the trial process. Evidence that is otherwise logically relevant may be excluded on this basis if its probative value is overborne by its prejudicial effect, if it involves an inordinate amount of time which is not commensurate with its value or if it is misleading in the sense that its effect on the trier of fact, particularly a jury, is out of proportion to its reliability.

    This concept of weighing the cost and benefits of evidence as part of the relevance inquiry has been described as “legal relevance” as opposed to “logical relevance”.6


    The “necessity” criterion involves an inquiry into whether the evidence is necessary in the sense that it is required because the subject area is outside the experience and knowledge of the trier of fact. In R. v. Mohan Justice Sopinka quoted the following excerpt from R. v. Abbey on the issue of necessity:7

    With respect to matters calling for special knowledge, an expert in the field may draw inferences and state his opinion. An expert’s function is precisely this:  to provide the judge and jury with a ready-made inference which the judge and jury, due to the technical nature of the facts, are unable to formulate.

    It is not enough that the expert evidence might be “helpful”. The Supreme Court made it clear in R. v. Mohan that helpfulness would set too low a standard for the admission of expert evidence.  Expert evidence is necessary where the subject matter is such that ordinary people are unlikely to form a correct judgment about it without guidance from an expert.8

    Where the subject matter of the evidence is technical, scientific or medical and clearly outside of the scope of lay knowledge necessity is obvious. Where the subject matter is less far removed from lay knowledge, the question of whether the expert evidence is necessary is more difficult.

    In Greenhalgh v. Douro-Dummer (Township)9 it was alleged that a municipality ought to have erected clearer signage to warn that a road ended. Both the plaintiffs and the defence called “human factors” experts to opine on how drivers would be expected to react to the signs that were in place. While Justice Lauwers admitted the evidence, he found it to be of little assistance:

    I give relatively little weight to the evidence of the human factors experts. To a large extent, they were informed advocates for their respective clients and testified on some of the very questions that I must decide. The amount of real expertise involved in their evidence was minimal.

    Expert evidence on a subject that can be easily understood by lay people without the opinion of an expert may not meet the test of necessity. No objection was made to the admission of the human factors evidence in the Greenhalgh case, which was a trial by Judge alone. Whether or not this sort of evidence would withstand an objection on the necessity test in a jury trial would be questionable given Justice Lauwers’ comments about its value.

    Expert evidence is not unnecessary under Mohan simply because there are multiple experts opining on the same issue. In the case of Taylor v. Sawh10 the trial judge ruled that a police reconstruction expert could not offer opinion evidence on the basis that it was unnecessary under the Mohan test because two more qualified accident reconstruction experts would testify at trial. The Court of Appeal overruled the decision and said the following on the issue of multiple reconstruction experts testifying:

    The opinion of a qualified expert does not become unnecessary simply because there may be other, even more qualified experts, who will be testifying at trial.

    As Justice Di Tomaso stated in Laudon v. Roberts, “necessity is to be judged according to whether the particular kind of evidence being offered meets the necessity requirement, not according to whether other experts have already filled the need for expert testimony”.11


    In the case of R. v. Abbey12 Justice Doherty, writing for a unanimous Court of Appeal panel, analyzed R. v. Mohan and the cases that have followed it.  Justice Doherty characterized the Mohan test as a two part exercise. The first part of the exercise involves answering the straight forward “yes” or “no” questions about whether the evidence is logically relevant, whether the expert is properly qualified and whether the evidence offends any exclusionary rule.

    Justice Doherty described the second part of the exercise as the “gatekeeper” inquiry. This involves considerations of legal relevance and necessity and a cost-benefit analysis:13

    The “gatekeeper” inquiry does not involve the application of bright line rules, but instead requires an exercise of judicial discretion. The trial judge must identify and weigh competing considerations to decide whether on balance those considerations favour the admissibility of the evidence. This cost-benefit analysis is case-specific and, unlike the first phase of the admissibility inquiry, often does not admit of a straightforward “yes” and “no” answer.

    Justice Doherty indicated that the cost-benefit analysis should involve both questions pertaining to legal relevance (ie. probative value and prejudicial effect) and necessity:14

    The cost-benefit analysis demands a consideration of the extent to which the proffered opinion evidence is necessary to a proper adjudication of the fact(s) to which that evidence is directed.   In Mohan, Sopinka J. describes necessity as a separate criterion governing admissibility. I see the necessity analysis as part of the larger cost-benefit analysis performed by the trial judge.  

    Justice Doherty described the “cost” and “benefit” parts of the cost-benefit evaluation as follows:15

    The “cost” side of the ledger addresses the various risks inherent in the admissibility of expert opinion evidence, described succinctly by Binnie J. in J.(J.), at para. 47 as “consumption of time, prejudice and confusion”. Clearly, the most important risk is the danger that a jury will be unable to make an effective and critical assessment of the evidence.

    The “benefit” side of the cost-benefit evaluation requires a consideration of the probative potential of the evidence and the significance of the issue to which the evidence is directed. When one looks to potential probative value, one must consider the reliability of the evidence. Reliability concerns reach not only the subject matter of the evidence, but also the methodology used by the proposed expert in arriving at his or her opinion, the expert’s expertise and the extent to which the expert is shown to be impartial and objective.  

    The extent to which the evidence is necessary to assist the jury understand the subject matter is a part of the cost-benefit evaluation described by Justice Doherty:

    In many cases, the proffered opinion evidence will fall somewhere between the essential and the unhelpful. In those cases, the trial judge’s assessment of the extent to which the evidence could assist the jury will be one of the factors to be weighed in deciding whether the benefits flowing from admission are sufficiently strong to overcome the costs association with admission. 

    In summary, the following factors are to be examined in the cost-benefit analysis described by Justice Doherty:

    1. How significant is the issue to which the evidence is directed?
    2. How reliable is the evidence?
      • Is the subject matter of the evidence an established or novel science?
      • Is the expert’s methodology reliable?
      • Does the expert’s level of expertise bear on the evidence’s reliability?
      • Are there issues with the expert’s impartiality and objectiveness that would impact on reliability?
    3. How much time will the evidence take?
    4. Is there potential that the evidence will result in prejudice?
    5. Is there potential that the evidence will confuse the jury?
    6. To what extent is the evidence necessary for the jury to understand the subject matter?


    The authors of The Law of Evidence in Canada point out that the factual basis of an expert’s opinion may be derived from the following three possible sources:

    1. The firsthand knowledge of the expert;
    2. The evidence adduced at trial with factual premises incorporated into hypothetical questions; and
    3. Information or data presented outside court other than by the expert’s own perception.

    With respect to firsthand knowledge, a medical expert who assesses a plaintiff is entitled to give evidence about his or her findings and the opinions that flow from those findings. Similarly, an engineering expert who has surveyed an accident scene is entitled to give evidence about his or her survey and the opinions that flow from it.

    A more perplexing issue arises when experts have based their opinions on hearsay evidence that is not proven in Court.   Medical experts often base their opinions on medical records. Usually those records are admitted into evidence and there is no issue.   However, where the facts that an expert has relied upon are not admitted into evidence problems arise.

    In R. v. Lavallee the defence called a psychiatrist to testify about battered woman’s syndrome.   The psychiatrist based his evidence on hospital records and a police report which were admitted into evidence.   However, he also relied upon interviews with the accused and her mother, neither of whom testified at trial.   The issue was whether this hearsay evidence should have been admitted through the psychiatrist and whether the expert’s opinion was admissible given his reliance on hearsay evidence.

    The Supreme Court reviewed the case law relating to foundational facts and distilled the law into the following propositions:16

    1.  An expert opinion is admissible if relevant, even if it is based on second-hand evidence;
    2.  This second-hand evidence (hearsay) is admissible to show the information on which the expert opinion is based, not as evidence going to the existence of the facts on which the opinion is based;
    3.  Where the psychiatric evidence is comprised of hearsay evidence, the problem is the weight to be attributed to the opinion;
    4.  Before any weight can be given to an expert’s opinion, the facts upon which the opinion is based must be found to exist.

    The fourth proposition does not mean that all of the facts underlying the opinion must be proven before any weight is given to the opinion. If some of the factual foundation is proven and some is not, the failure to prove part of the factual foundation goes to weight. Justice Wilson made this clear in Lavallee:

    The fourth proposition I have extracted from Abbey is that there must be admissible evidence to support the facts on which the expert relies before any weight can be attributed to the opinion.   The majority of the Manitoba Court of Appeal appears to interpret this as a requirement that each and every fact relied upon by the expert must be independently proven and admitted into evidence before the entire opinion can be given any weight.

    If the majority of the Court of Appeal is suggesting that [all facts relied upon] must be proven in evidence before any weight could be given to Dr. Shane’s opinion about the accused’s mental state, I must respectfully disagree…In my view, as long as there is some admissible evidence to establish the foundation for the expert’s opinion, the trial judge cannot subsequently instruct the jury to completely ignore the testimony.   The judge must, of course, warn the jury that the more the expert relies on facts not proved in evidence the less weight the jury may attribute to the opinion.  

    Therefore, so long as there is some admissible evidence to establish the foundation of the opinion, the opinion evidence is admissible. The failure to prove parts of the factual foundation of an opinion goes to weight.

    The issue of proof of foundational facts arose in the medical malpractice case of Marchand v. Public General Hospital Society of Chatham.17  In that case, the plaintiffs sought to introduce opinion evidence from two home care experts who had based their opinions on reports from various medical practitioners.   The reports of the medical practitioners upon which the opinions were based were not entered into evidence (and there was no plan to enter them into evidence).   The trial judge refused to hear the opinion evidence on the basis that the entire factual foundation of the opinions was hearsay.  The Court of Appeal upheld this ruling.   The Court of Appeal confirmed that Lavallee provides that “proof of foundational facts goes to the weight to be accorded to the opinion rather than its admissibility”.   However, where none of the foundational facts are proven the opinion can be given no weight and should not be admitted.


    Many judges have expressed concern about the proliferation of expert evidence in both criminal and civil cases.

    In R. v. Mohan Justice Sopinka expressed the concern that juries may tend to give expert evidence undue weight:18

    Dressed up in scientific language which the jury does not easily understand and submitted through a witness of impressive antecedents, this evidence is apt to be accepted by the jury as being virtually infallible and as having more weight then it deserves. 

    In R. v. J.J. Justice Binnie stressed the importance of the gatekeeper role of the trial judge in deciding whether or not to admit expert opinion evidence: 19

     In the course of Mohan and other judgements, the Court has emphasized that the trial judge should take seriously the role of “gatekeeper”.   The admissibility of the expert evidence should be scrutinized at the time it is proffered, and not allowed too easy an entry on the basis that all of the frailties could go at the end of the day to weight rather than admissibility.

    In these criminal cases, the Supreme Court was concerned about the negative impact of expert evidence of questionable reliability on the trial process.   In civil cases, the increasing use of expert evidence raises another concern: costly expert-driven litigation threatens access to justice for some litigants.

    On June 28, 2006 Attorney General Michael Bryant asked Justice Coulter Osborne to propose options to reform the civil justice system to make it “more accessible and affordable” for Ontarians.   In November 2007 Justice Osborne released his report entitled Civil Justice Reform Project: Summary of Findings & Recommendations (the “Osborne Report”)

    Justice Osborne expressed a number of concerns about the use of expert evidence in civil proceedings.   Most significant among those concerns were the following:

    • There has been an undue proliferation of experts;
    • There is a problem with expert bias;
    • Expert reports are not standardized;  and
    • The timing of service of expert reports does not promote early settlement.

    Justice Osborne made a number of recommendations to deal with these issues.   These recommendations led to significant changes to the Rules of Civil Procedure dealing with the use of expert evidence.20

    The realities relating to the use of expert evidence in civil proceedings are changing.   Judges are more carefully scrutinizing the number of experts called. Judges are becoming increasing wary of “hired gun” experts.   Judicial tolerance of non compliance with the rules relating to expert reports is waning.


    Justice Osborne identified the “proliferation” of experts as leading to increased litigation cost and increased trial time:21

    There has been a proliferation of expert reports.   The culture of litigation has resulted in an “industry” of competing experts, which unduly increases costs.

    The vast majority of those consulted in the course of this Review identified the proliferation of experts as a significant problem that often leads to a battle of competing experts.  Some observed that as soon as one party retains an expert, an opposing party is forced to retain an expert.   The expert merry-go-round bears with it an advantage to a litigant who has significant financial resources.   

    This concern led Justice Osborne to consider recommending changes to section 12 of the Evidence Act.   That provision provides as follows:

     12.       Where it is intended by a party to examine as witnesses persons entitled, according to the law or practice, to give opinion evidence, not more than three of such witnesses may be called upon either side without the leave of the judge or other person presiding.

    Justice Osborne considered whether or not to recommend making a strict three expert per case rule.    He rejected this idea, pointing out that it would be impossible to effectively present a serious personal injury case with only three experts:22

    Personal injury trials provide a useful example.   In those actions it is frequently necessary to call more than three doctors.   In addition, actuarial evidence is often required where there are future loss claims.   Many personal injury claims raise “level of care” and more general “future care” costs issues.   It is difficult to contemplate a serious personal injury case being presented (or defended) without more than three expert witnesses. 

    While Justice Osborne acknowledged the need to call more than three experts is necessary in many trials, he expressed concern that the existing provision leaves this decision to the trial judge.    This means that the parties do not know how many expert witnesses they will be permitted to call until they get to trial.   Justice Osborne recommended that the provision be amended to allow this decision to be made before trial (by the pre-trial judge or trial management judge).  He also recommended that section 12 be amended to list the following factors for the Court to consider in exercising its discretion on the appropriate number of experts:

    i)          Whether the proposed number of experts is reasonably required for the fair and just resolution of the proceeding.

     ii)         Whether the proposed number of experts is consistent with the principle of keeping costs and the length of the proceeding proportionate to the amount or issues at stake.

     iii)        Any other factors relevant to the fair, just, expeditious and cost effective resolution of the proceeding.  

    The government has not yet amended section 12 of the Evidence Act.   However, changes have been made to the Rules of Civil Procedure to permit a determination of the number of experts to be allowed to testify to be made prior to trial.    Rule 50.06.8 now provides as follows:

    50.06   The following matters shall be considered at the pre-trial conference:

    8.  In the case of an action, the number of expert witnesses and other witnesses that may be called by each party, and the dates for the services of any outstanding or supplementary expert reports.  

    Counsel must now come to the pre-trial prepared to address the issue of the appropriate number of expert witnesses to be called at trial. Counsel must also be aware of a number of recent cases dealing with the interpretation of section 12 of the Evidence Act.

    In the case of Burgess v. Wu23 Justice D. Ferguson dealt with an application for leave to call more than three expert witnesses in a medical malpractice claim. The plaintiff argued that section 12 of the Evidence Act should be interpreted as limiting a party to three expert witnesses per issue rather than three expert witnesses total. This submission was rejected by Justice Ferguson.   The law in Ontario is now fairly well settled that section 12 of the Evidence Act requires leave of the trial Judge to call more than three experts in total (as opposed to three experts per issue).24

    Justice Ferguson granted the plaintiff leave to call two family physicians, two psychiatrists and two pharmacologists to address the liability issues in the case. In doing so, he set out the following factors to be considered in granting leave to call more than three experts:

     i)          Whether the opposing party objects to leave being granted.

     ii)         The number of expert subjects in issue.

     iii)        The number of experts each side proposes to have opine on each subject.

     iv)        How many experts are customarily called in cases with similar issues?

     v)         Whether the opposing party will be disadvantaged if leave is granted because the applying party will then have more experts than the opposing party.

     vi)        Is it necessary to call more than three experts in order to adduce evidence on the issues in dispute?

     vii)       How much duplication is there in the proposed opinions of different experts?

     viii)      Is the time and cost involved in calling the additional experts disproportionate to the amount at stake in the trial?

    The last factor (proportionality) is a particularly important one in light of the Osborne Report and the recent changes made to the Rules of Civil Procedure.    The overriding theme of the Osborne Report is the need for proportionality in civil litigation (ie. the time and expense devoted to a proceeding ought to be proportionate to what is at stake).    The concept of proportionality is now an overriding principle in applying the Rules of Civil Procedure.   Rule 1.04(1.1) reads as follows:

    In applying these rules, the court shall make orders and give directions that are proportionate to the importance and complexity of the issues, and to the amount involved, in the proceeding.

    The second to last factor listed by Justice Ferguson is also very important.   Recent cases have made it clear that Judges are more likely to allow multiple experts where their opinions are not repetitive or where their qualifications are different.

    In Repic v. Hamilton (City)25 the defendant municipality objected to the plaintiffs’ plan to call four expert witnesses on liability issues in a faulty road design case. The plaintiffs intended to call an accident reconstruction engineer, two road design experts and a human factors engineer. Justice Walters granted leave for the plaintiffs to call all four experts on the basis that the subject matter of their evidence was distinct from each other:

     Specifically, I was satisfied that each of the proposed expert witnesses would testify about a distinctive topic…

     The issues in this lawsuit were complex and not something with which the court was familiar.    The road design in question was undertaken over a number of years and involved planning by an array of experts.

     In my view, the four proposed witnesses would not seriously lengthen the trial.   The time and expense associated with their evidence was not disproportionate to the issues and seriousness of this case.

    Where there is significant overlap in multiple experts’ qualifications and opinions it is more difficult to obtain leave under section 12 of the Evidence Act, even if the stakes are high.

    Suwary v. Woman’s College Hospital26 was a birth trauma malpractice case with damages claimed in excess of $30 million.   The plaintiffs hoped to call four obstetricians to address the complicated standard of care questions in the case.   Justice Moore allowed only two of these experts to testify.   He found that the evidence from the other two would be unduly repetitious and refused to grant leave:27

    The overlap in the evidence sought to be led through these two doctors is so substantial as to be overwhelming.   Moreover, a comparison of the proposed evidence of these doctors to that already heard from Doctors Harman and McGrath leads to the inescapable conclusion that every single criticism that might be made of Dr. Librach’s conduct by Dr. Carson and/or Dr. Fruitman is already the subject of expert evidence, heard over the course of several days during the trial of this action.   Hearing the same evidence over the course of several more days is neither necessary or helpful. 

    Goodwin v. Olupona28 was another birth trauma malpractice case.   The plaintiffs sought to call three obstetricians on the issue of standard of care.   After reviewing the reports from those three experts Justice Glass decided that only one could testify, on the basis that “the three proposed experts have similar reports and cover similar information”.29   On the issue of causation, the plaintiffs proposed to call two neonatologists, two paediatric neurologists, an infectious disease expert and a paediatric radiologist.   Justice Glass accepted that the physicians from different specialties would each address different areas.   However, he found the plaintiff should be limited to one neonatologist and one paediatric neurologist because calling two of each specialty would be “likely to overload the jury with duplication of information and eventually confuse the jurors”.30

    These cases, and others,31 make it clear that obtaining leave to call more than three experts under section 12 of the Evidence Act is not a formality.    However, they should not be taken as saying that it is never appropriate to call two similarly qualified experts to address an issue.   Indeed, in the Suwary case Justice Moore concluded that it is sometimes necessary to have multiple experts on the same issue to fill in gaps in the evidence:32 

    Clearly, not all of the evidence contained within the four corners of medical legal reports authored during the course of a medical malpractice action can be predicted, with any degree of certainty, to represent the evidence that medical experts might ultimately be heard to give at trial.   I accept that in a proper case, it may be entirely appropriate to obtain multiple reports in order that gaps anticipated in the evidence of one expert witness may be filled in through the evidence ultimately heard from another expert witness.

    The key to dealing with motions for leave under section 12 of the Evidence Act is to know your experts’ qualifications (and how they differ), know your experts’ reports (and how they differ) and to be prepared to address the factors set out by Justice Ferguson in the Burgess v. Wu case


    In the case of Frazer v. Haukioja33 Justice Moore described the importance of experts being impartial:34

    Whatever role the expert may have undertaken during the course of the litigation in assisting counsel to a fuller appreciation of the facts in dispute and the inferences that might be drawn from them, the expert must set aside that role upon entering the witness box at trial.   From the witness box the expert speaks only to assist the court.

    Because the opinions stated by an expert are predicated upon expertise that the court does not possess, the court must be confident in relying upon the expert to provide a thorough, balanced and technically sound analysis.  Independence and impartiality; the court expects nothing more and it will accept nothing less.

    Advocacy on the part of experts has long been frowned upon.  As Justice Spiegel pointed out in Southcott Estates Inc. v. Toronto Catholic District School Board many judges have admonished experts for being advocates:35

    Qualified expert witnesses are granted a right not available to lay witnesses; to give express opinions for the assistance of the court.   But with this right comes the crucially important responsibility of maintaining an attitude of strict independence and impartiality…Simply put, this means that the expert opinions should not be influenced by the interests of the party calling him or her…For more than a decade, the cases have contained similar admonitions.   Regrettably, I have not noticed any significant improvement in the manner in which expert witnesses have been discharging their responsibilities. 

    More often than not, Judges will reject the evidence of experts who they view as partisan.  The criticism of these experts is often scathing.36  

    The issue of expert bias was identified as a significant problem in the Osborne Report:

    The issue of “hired guns” and “opinions for sale” was repeatedly identified as a problem during consultations.  

    Identifying the problem is easy. Finding a solution to the problem is much more challenging. Justice Osborne recommended that the Rules of Civil Procedure be amended to impose an express duty on experts to be independent and impartial:37 

    To help curb expert bias, there does not appear to be any sound policy reason why the Rules of Civil Procedure should not expressly impose on experts an overriding duty to the court, rather than to the parties who pay or instruct them.   The primary criticism of such an approach is that, without a clear enforcement mechanism, it may have no significant impact on experts unduly swayed by the parties who retain them.  

     An expressly prescribed overriding duty to provide the court with a true and complete professional opinion will, at a minimum, cause experts to pause and consider the content of their reports and the extent to which their opinions may have been subjected to subtle or overt pressures.

    The government responded to this recommendation by adding Rule 4.1 of the Rules of Civil Procedure.   This new rule provides that experts are under a duty to provide evidence that is “fair, objective and non-partisan”, and to limit their evidence “to matters that are within the expert’s area of expertise”.   Rule 53.03 was revised to make it mandatory for every expert to sign a form acknowledging the duty set out in Rule 4.1 (Form 53).

    The idea that an expert witness must be fair, objective and non-partisan is nothing new.38   However, the fact that this duty must now be expressly acknowledged by experts is bound to lead judges to be less tolerant of hired gun experts.

    Rule 53.03 was also amended to standardize the content of expert reports.39   Expert reports must now include the following:

    • The expert’s name, address and area of expertise;
    • The expert’s qualifications and employment and educational experiences in his or her area of expertise;
    • The instructions provided to the expert in relation to the proceeding;
    • The nature of the opinion being sought and each issue in the proceeding to which the opinion relates;
    • The expert’s opinion respecting each issue and, where there is a range of opinions given, a summary of the range and the reasons for the expert’s own opinion within that range;
    • The expert’s reasons for his or her opinion, including:
      • A description of factual assumptions;
      • A description of research done; and
      • A list of documents relied upon.

    These amendments are intended to make the instructions given to experts transparent and to ensure that experts properly explain the basis for their opinions, again with a view to eliminating advocacy in favour of impartiality.

    Justice Osborne also recommended that the Rules of Civil Procedure be amended to allow a judge to order competing experts to “meet and confer”:40 

    During consultations, medical experts noted that doctors often work well in forming consensus.   They suggested that it would be very useful to have experts meet to consider whether issues can be agreed upon and determine which are still in dispute.   For all experts, this reform would provide a level of peer review that expert opinions do not routinely undergo.   It may also assist in clarifying disparate interpretations of underlying facts and assumptions…

    This recommendation was adopted by the Rules Committee.   The combination of Rules 50.07(1)(c) and 20.05(2) now provide a pre-trial judge with the authority to order that experts meet, on a without prejudice basis, for the following purpose:

     …in order to identify the issues on which the experts agree and the issues on which they do not agree, to attempt to clarify and resolve any issues that are the subject of disagreement and to prepare a joint statement setting out the areas of agreement and any areas of disagreement and the reasons for it…

    Justice Osborne was of the view that these meetings “would introduce a level of accountability that may deter ‘hired guns’”. It remains to be seen how these meet and confer meetings will work in practice.

    The new Rules raise important ethical considerations for lawyers relating to their pre-trial dealings with experts. Justice Osborne expressed concerns about experts being influenced by the lawyers who instruct them. Counsel must be wary of pressuring experts to change their opinions. Even the appearance of pressure by a lawyer on an expert can be damaging when it comes time for the expert to testify.

    In Frazer v. Haukioja Justice Moore called into question the impartiality of an expert on the basis that he spent several hours on the phone with his instructing counsel before writing his report:41

    The independence of Dr. Neal rises to a level of concern for the court since the doctor has chosen to include reference in his C.V. to the fact that he is a medical expert for the law firm that retained him in this case and, as well, by his agreement to provide a formal opinion to counsel in writing only after discussing his views with counsel orally.

     Dr. Neal’s impartiality is called into question by his having had several hours of telephone conversations and a meeting with counsel before preparing his reports…

    Talking to an expert prior to the preparation of a report is normal practice.   However, any attempt to influence an expert’s opinion will be frowned upon. An expert who allows his or her opinion to be influenced in a material way risks being labelled as an advocate.

    It is important that counsel work with expert witnesses so that they avoid giving the appearance of an advocate. Experts who give unresponsive answers and who quibble with the obvious are likely to be quickly categorized as partisan. The description of the evidence of an expert by Justice Spiegel in Southcott Estates Inc. v. Toronto Catholic District School Board is illustrative of witness demeanour likely to offend a trial judge:42

    I agree with the plaintiff’s submission that Mr. Dragicevic departed from the role of an independent and impartial advisor to the court and adopted the role of an advocate for the defendant.   His answers to questions in cross-examination were often not responsive.   He quibbled and often appeared unwilling to accept the obvious.  

    Experts must ensure that they obtain all of the necessary documents and review them with a critical eye, rather than simply accepting information from a litigant.   In the case of Love v. Acuity Investment Management Inc.43 the evidence of a forensic accountant was rejected because he accepted information provided by the plaintiff without auditing it for accuracy.

    Counsel must also be wary of relying on experts who have a relationship to the litigant.    Gutbir v. University Health Network44 was a birth trauma malpractice claim.   The cause of the infants’ brain injury was a key issue.   The plaintiff obtained a medical-legal report from the treating neonatologist, Dr. Perlman, on the issue of causation.   Defence counsel objected to Dr. Perlman giving opinion evidence on the basis that he lacked the objectivity necessary to permit him to be called as an expert.

    Justice D. Wilson found that the new Rule 53.03 imposes a higher standard for impartiality than previously existed:45

    In my view, it is clear that the amendments that were made to Rule 53.03 in January of 2010 were to address a number of problems that were frequently encountered by the courts when dealing with expert testimony, one of which was ensuring the impartiality of the expert opinion.  

    Counsel were candid in their acknowledgement that they were not aware of any decisions dealing with treating doctors qualified as experts in medical negligence cases tried with a jury since the amendments to Rule 53 in January 2010.  

    In permitting Dr. Perlman to offer an expert opinion in this case, the Court must be satisfied that the more stringent requirements of the amended Rule 53.03 have been met.  

    Justice Wilson found that as a treating physician Dr. Perlman lacked the impartiality necessary to give expert evidence under Rule 53.03.    The case cannot be taken as laying down an absolute rule that treating doctors cannot give expert evidence on the matters at issue in a lawsuit.   Justice Wilson pointed out in her reasons that Dr. Perlman’s report contained comments of the sort an advocate would make.   These comments factored into her decision that Dr. Perlman lacked the objective necessary to offer an expert opinion.    However, the case must be considered by counsel relying on treating physicians to give expert evidence on a key issue.

    The case of Kusnierz v. Economical Mutual Insurance46 is a further recent example of the importance of keeping experts independent of litigants.   In that case a physiatrist, Dr. Ameis, testified for the plaintiff on the issue of whether the plaintiff was catastrophically impaired.   Dr. Ameis was initially retained by plaintiffs’ counsel to assist in preparing an accident benefits claim but, as Justice Lauwers points out, “moved from the status of an independent expert to something close to a treating physician”.   Justice Lauwers described Dr. Ameis as a “passionate advocate” for his patient.

    Justice Lauwers decided to admit the evidence but Dr. Ameis’ relationship to the plaintiff eroded the weight of his evidence:

    It would be reasonable in these circumstances, to consider the evidence of Dr. Ameis as one would the evidence of a treating physician like a family doctor. Such a witness does not seem to fall squarely within either Rule 4.1.01 or Rule 53.03, but is someone who has and exercises expertise routinely, and ought to be able to give relevant evidence about his or her patient. I will take into account that Dr. Ameis has been a passionate advocate for Mr. Kusnierz and has formed a therapeutic alliance with him.  I must, therefore, take his evidence with the proverbial grain of salt that goes to its weight.  

    All of these cases make it apparent that counsel must be vigilant to ensure that the independence and impartiality of their experts is maintained.


    The comment of Justice Lauwers in Kusnierz that treating doctors do not fall squarely within Rule 53.03 raises an important issue:   Can opinion evidence be provided by an expert witness who does not author a report and sign an acknowledgement of expert duty form as required by Rule 53.03?

    In Beasley v. Barrand47 defence counsel in a tort claim wanted to call three medical experts who had assessed the plaintiff in the course of insurer’s examinations requested by the plaintiff’s accident benefits insurer.   Those assessments occurred more than seven years before the trial.   The plaintiff objected to the proposed expert evidence on the basis that the experts’ reports did not comply with the new Rule 53.03.   The three experts had been retained by the accident benefits insurer.   Their reports were authored for the accident benefits insurer and were not prepared for the defence in the tort claim before Justice Moore.

    Defence counsel had the three experts sign acknowledgement of expert duty forms.   These forms require an expert to certify that he or she has been retained by or on behalf of one of the parties to the litigation to provide evidence in relation to the proceeding.   Because the experts had been retained by the accident benefits insurer and had prepared their reports for the accident benefits insurer, Justice Moore had difficulty with their signing the forms:48

    The original forms signed by Drs. Soric and Moddel confirm that they had been “engaged by or on behalf of” the insurance adjusters. The forms these doctors signed more recently state that they had been “engaged by or on behalf of the defendant…in relation to [this] court proceeding.  here is no contest that none of the three doctors had been retained by or on behalf of the defendants. These reports were not commissioned by any party to this action for the purposes of this action. 

    Justice Moore also had problems with the form and content of the expert reports. Rule 53.03 requires an expert to set out the reasons for his or her opinion including the factual assumptions made, the research done and the documents relied upon.    Justice Moore found that the expert reports failed to set out the basis for the opinions as required by the new Rules:49

    In any event, the basis for their optimism that Mr. Beasley would be able to meet the demands of the job is simply not addressed.  

    Defence counsel argued that any issue of non-compliance with Rule 53.03 was a violation of a technical, rather than a substantive requirement.   Justice Moore did not accept this submission. His Honour held that Rule 53.03 had been revised in order to rein in expert evidence, particularly evidence of questionable probative value:50

    In my view, the rule advances the law that has been developing in recent years toward reining in the growing use of and reliance upon the evidence of experts at trial. 

    Surely, one of the important reasons for the rule change was to eliminate the practice of tendering opinion evidence of questionable value in a trial, particularly where, as is the case here, the evidence was created in another proceeding, at the instance of a party who is not before this court and to address matters that are beyond the scope of this trial.

    Justice Moore found the opinions of the three proposed experts to be of limited probative value because of the length of time that had passed between the assessments and the trial.   He described the opinions as “snapshots of the plaintiff’s situation taken at a point more than seven years ago”.51   Given the age of the reports Justice Moore found that any probative value they had was outweighed by the prejudicial effect of the evidence:52

    I am not persuaded that the interests of trial fairness could be well served by allowing the three experts to testify;  the additional time, complexity and expense necessarily involved, when weighed against the prejudice to the plaintiff, prejudice that I find cannot be compensated for by costs or an adjournment…cannot be justified.

    In the circumstances of the Beasley case Justice Moore decided that the experts would not be allowed to testify.

    The Beasley decision should not be interpreted as saying that no expert can testify unless he or she is retained by the party in relation to the lawsuit and is in strict compliance with Rule 53.03. Justice Moore indicated that his analysis would have been different had he been dealing with a treating expert or an expert whose opinion was central to the outcome of the litigation:53

    We are not dealing here with the treatment related opinions formed in the course of providing primary care to a plaintiff and nor is the opinion of any of the three experts here so central to the outcome of the litigation as might be the opinion of an origin and cause expert [such as] an assistant fire chief in a case where negligence causing a building fire is alleged.

    Justice Moore expressly indicated in his reasons that he should not be taken as saying that an expert retained by an accident benefits insurer can never testify on behalf of a party in a tort claim.   His Honour indicated that counsel wanting to rely on opinions from those experts should attempt to get them to write meaningful reports, in compliance with Rule 53.03:[54]

    I suggested that the defendant s could invite the doctors, at the defendants’ expense, to write meaningful, Rule 53.03 compliant, reports to plaintiff’s counsel which, if relevant and producible, could help me to understand any opinions they might be able to express on issues between the parties before this Court.   That was not attempted.

    Justice Moore also recognized that there will be occasions where it is impossible to get a Rule 53.03 compliant report from an expert retained by a stranger to the litigation (eg. where the expert refuses to do it or cannot communicate with counsel because of confidentiality duties).   His Honour recognized that in those situations the expert will still be permitted to testify if the evidence is required for a fair adjudication of the case:55

    I am not to be heard to state that experts retained by accident benefits insurers cannot give opinion evidence in a tort action; rather, I say that such experts should first comply with Rule 53.03.   I say “should” for there may be cases where that is not possible and then the court might consider relieving against non-compliance to ensure a fair adjudication of the issues upon their merits but this is not one of those cases. 

    The issue of expert evidence from witnesses without a Rule 53.03 compliant report was also addressed in Slaght v. Phillips.56  In that case the plaintiff wanted to call a vocational rehabilitation counsellor who had assessed and provided vocational counselling to the plaintiff.  The defence objected to the proposed evidence, arguing that there was non-compliance with Rule 53.03.

    After hearing evidence on a voir dire Justice Turnbull characterized the vocational counsellor as a “treating expert witness”. Justice Turnbull found that Rule 53.03 was directed at “litigation opinions” rather than “treatment opinions”:

    I do not think I am alone in that opinion because my colleague, Ferguson J. of this court, in the case of Burgess v. Wu (2003) 68 O.R. (3d) 710 stated the distinction as follows:

    The qualifications I have added to the previous rulings is to take account of the fact that when a physician attends on a patient the process typically involves making a diagnosis, formulating a treatment plan and making a prognosis.   All three involve forming opinions.   Those are different from the opinions an expert is asked to provide at trial as the latter usually involve a consideration of much more information from various sources and are formed for the purpose of assisting the court at trial and not for the purpose of treatment.   I shall call opinions formed at the time of treatment “treatment opinions” and those formed for the purpose of litigation “litigation opinions”

    In my view, the purpose of Rule 53.03 is much more directed at the latter opinions rather than at the prior opinions.

    Justice Turnbull categorized experts as falling into four groups in terms of the obligation to comply with Rule 53.03.    Those groups and Justice Turnbull’s comments on the applicability of Rule 53.03 to each group is as follows:

    • Treating Witnesses:   These are people who provide treatment, form opinions about treatment and keep clinical notes and records.   The requirements of Rule 53.03 do not apply to these witnesses provided they limit their evidence to treatment opinions.
    • Experts Retained by the Parties:    The requirements of Rule 53.03 clearly apply to these witnesses.
    • Experts Retained by Third Parties:   These include experts retained by accident benefits insurers (as in Beasley) or disability insurers.   The requirements of Rule 53.03 apply to these witnesses subject to the Court relieving against non-compliance to ensure a fair adjudication of the case.
    • Treating Witnesses Who Are Paid By and Who Report to Third Parties.   This was the situation in Slaght.   The vocational counsellor provided regular reports to the accident benefits insurer to update the insurer on the case and to secure additional funding.  The requirements of Rule 53.03 do not apply to these witnesses provided they limit their evidence to treatment opinions.

    Counsel must have regard to the Beasley and Slaght cases when determining the expert evidence to be called at trial.   Where an expert is offering a litigation opinion as opposed to a treatment opinion it is essential that the requirements of Rule 53.03 be met.


    Justice Osborne determined that the old Rules governing the delivery of expert reports were problematic:57

    The timing of delivery of expert reports under the current rules does not promote early settlement and may result in late requests for trial adjournments.   Rule 53.03 requires a party who intends to call an expert to serve opposing parties with a copy of the expert’s report not less than 90 days before trial.   A party who intends to call an expert to testify in response must serve a responding expert report not less than 60 days before trial.   Any supplementary report must be served not less than 30 days before trial.   Anchoring these tight timelines to the trial event has been cited as a major problem for both litigants and experts, resulting in last-minute requests for trial adjournments.  

    Justice Osborne was of the opinion that anchoring the time-lines to the pre-trial would be preferable.  However, he recognized that the timing of pre-trial conferences is variable and that if the pre-trial is too far in advance of the trial date, expert reports will need to be updated causing further expense to the litigants.

    Ultimately, Justice Osborne recommended that the timing of the delivery of expert reports be left up to the agreement of counsel and where no agreement can be reached that the 90/60/30 rule be anchored to the pre-trial.

    The Rules Committee adopted these recommendations. Rule 53.03(2.2) now provides that within 60 days after an action is set down the parties agree to a schedule setting out dates for the service of expert reports. Rules 53.03 (1) and (2) set out the default rule for the service of expert reports.   Reports must be served 90 days prior to the pre-trial. Responding reports must be served 60 days prior to the pre-trial. Rule 53.03(3) provides that supplementary reports must be served not less than 30 days before trial.

    The changes relating to the timing of expert reports are intended to facilitate earlier settlement. They may result in additional expense to the parties in cases where there is a substantial delay between the pre-trial and the trial date due to the need to update expert opinions.


    There is little doubt that judicial attitudes towards expert evidence have changed in the last decade. Given the trend towards reining in unnecessary expert evidence and expert evidence that is not impartial, it is important to carefully consider the impact of the new Rules and recent case law when retaining experts and preparing them for trial.

    Counsel should be wary of retaining multiple experts with similar qualifications to address the same subject matter.   There is no guarantee that repetitive opinions from similarly qualified experts will be permitted at trial.

    Counsel should be careful to consider impartiality and independence issues when choosing an expert, instructing the expert and preparing the expert for trial. Caution should be exercised when relying upon an expert who has a relationship with a litigant.   Instructing experts must be done in a way that cannot be characterized as attempting to influence the expert’s opinion. All experts should be prepared for trial to avoid witness demeanour likely to lead a judge to label them as an advocate.

    Finally, the requirements of Rule 53.03 must be carefully considered. There is considerable risk that an expert offering a “litigation opinion” may not be permitted to testify unless his or her report meets the requirements of Rule 53.03 and he or she has properly completed a Form 53.


    1. Bryant, Lederman and Fuerst, The Law of Evidence in Canada, 3rd ed. (Toronto: LexisNexus, 2009), at pp. 771-772.
    2. Ibid, at p. 785.
    3. Ibid, see the cases at footnote 76.  
    4. [1994] 2 S.C.R. 9, at para. 17.
    5. Ibid, at para. 18.
    6. See R. v. Abbey (2009), 97 O.R. (3d) 330 (C.A), at para.82.
    7. R. v. Abbey, [1982] 2 S.C.R. 24, at p. 42.
    8. R. v. Mohan, supra note 4, at para. 22.
    9. [2009] O.J. No. 5438 (S.C.J.).
    10. [2000] O.J. No. 257 (C.A.).
    11. [2007] O.J. No. 1702 (S.C.J.), at para. 31.
    12. (2009) 97 O.R. (3d) 330 (C.A.).
    13. Ibid, at para. 79
    14. Ibid, at para. 93
    15. Ibid, at paras. 87, 90.
    16. R. v. Lavallee, [1990] S.C.J. No. 36, at para. 66.
    17. [2000] O.J. No. 4428 (C.A.)
    18. R. v. Mohan, supra note 4, at para 19.
    19. [2000] S.C.R. 600, at para. 28.
    20. The changes were made by Ontario Regulation 438/08 and Ontario Regulation 394/09.
    21. Osborne Report, pp. 69, 71.
    22. Osborne Report, p. 68.
    23. [2005] O.J. No. 929 (S.C.J.).
    24. See also Bank of America v. Mutual Trust Co, [1998] O.J. No. 1542 (Gen. Div.);  Goodwin v. Olupona [2010] O.J. No. 3919 (S.C.J.).
    25. [2010] O.J. No. 117 (S.C.J.).
    26. [2009] O.J. No. 553 (S.C.J.).
    27. Ibid, at para. 33.
    28. [2010] O.J. No. 2919 (S.C.J.).
    29. Ibid, at para. 8.
    30. Ibid, at para. 9.
    31. See Marsland v. Nochezi, [1995] O.J. No. 5119 (Gen Div.) in which Justice Klowak limited the plaintiff to calling one of three orthopaedic surgeons. See Igbokwe v. Price (2003), 36 C.P.C. (5th) 147 (S.C.J.) in which the plaintiff was limited to three of five proposed witnesses. See Gorman v. Powell, [2006] O.J. No. 4233 (S.C.J.) in which the plaintiff was limited to calling one of two orthopaedic surgeons.
    32. Supra, note 14, at para. 34.
    33. [2008] O.J. No. 3277 (S.C.J.).
    34. Ibid, at para. 138-139.
    35. [2009] O.J. No. 428 (S.C.J.), at para. 110.
    36. See for example Guerrero v. Fukuda, [2008] O.J. No. 3799 (S.C.J.), in which Justice Little described the evidence of a defence physiatrist as “a classic example of a highly qualified doctor with a pre-existing bias, appearing as a hired gun to discredit [the plaintiff].”
    37. Osborne Report, pp. 75-76.
    38. There are many statements of this principle in Canadian cases.   A very good summary of the duties of an expert witness can be found in the English case The Ikarian Reefer, [1993] 2 Lloyds Rep. 68 (QB), approved [1995] 1 Lloyds Rep. 455 (C.A.).
    39. 53.03(2.1)
    40. Osborne Report, p. 77.
    41. Supra, note #, para. 142-143.
    42. [2009] O.J. No. 428 (S.C.J.), at para. 107.
    43. [2009] O.J. No. 2288 (S.C.J.).
    44. [2010] O.J. No. 4982 (S.C.J.).
    45. Ibid, at paras. 12,16 and 31.
    46. [2010] O.J. No. 4462 (S.C.J.).
    47. [2010] O.J. No. 1466 (S.C.J.).
    48. Ibid, at para. 14.
    49. Ibid, at para. 32.
    50. Ibid, at para. 52.
    51. Ibid, at para. 35.
    52. Ibid, at para. 36.
    53. Ibid, at para. 64.
    54. Ibid, at para. 68.
    55. Ibid, at para. 70.
    56. Unreported decision of Justice Turnbull dated May 18, 2010.
    57. Osborne Report, p. 47.

    About the Author

    Troy Lehman

    A graduate of the University of Western Ontario law school, Troy was called to the bar in 2001. Troy received the highest mark on the Bar Admission course by anyone from Western University. Troy...

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