Chapter 9 – Forensic Evidence and Expert Testimony

I. Introduction

It is clear that the expert witness has become a fixture in our criminal justice system. As trials become increasingly more complicated, expert witnesses often are called upon to assist triers of fact by offering expert opinions based on their acquired “specialized knowledge.” Unquestionably, this movement towards increasing reliance on expert witnesses parallels the more relaxed approach to the admission and acceptance of this type of evidence by all parties involved in the criminal justice system.

We need to rethink our approach to expert witnesses and expert testimony. The very reason that courts rely on expert witnesses – for their specialized knowledge – makes it difficult to challenge their expertise and opinions. Checks and balances are required to overcome this frailty and the danger of creating “battles of the experts.” The recommendations from the Inquiry into Pediatric Forensic Pathology highlight the need for all participants in the criminal justice system to exercise vigilance and caution in assessing expert opinion evidence to ensure that it meets the standards of excellence required to guard against wrongful convictions. Indeed, the testimony at the Inquiry revealed with stark clarity that the role of the expert may not be fully understood by justice system participants, especially the expert, Dr. Charles Smith,Footnote 281 previously hailed as Ontario’s top pathologist in pediatric death cases, testified that he never received formal instruction on giving expert evidence; he believed that his role was to act as an advocate for the Crown and to “make a case look good.”Footnote 282

It is clear from these developments that the following premise bears repeating: regardless of who retains the expert, the expert witness’ role is not to take sides, but to provide an objective and balanced opinion. As noted by Commissioner Goudge, “[t]he role is a neutral one, at all stages of involvement, not just when testifying… [They] must understand that their role as experts in the criminal justice system is to provide the police, the Crown, the defence, and the court with a reasonable and balanced opinion, and to remain independent in doing so. The expert cannot become a partisan.”Footnote 283

Understanding this principle will assist experts greatly as they interact with other players in the criminal justice system. It is the first step towards clearly defined boundaries and limits that, in turn, help courts identify and assess reliability issues associated with proffered expert opinion evidence within the context of the criminal justice system.

Although these themes were discussed in the 2005 Report, they have gained prominence as a result of recent inquiries and court decisions.

II. 2005 Recommendations

  1. Prosecutors should receive training on the proper use, examination and cross-examination of expert witnesses during ongoing and regular education sessions.
  2. The Heads of Prosecutions Committee should consider the feasibility of establishing a national central repository to catalog and track, among others:
    • case law;
    • newsletters and articles;
    • reliability of current techniques,
    • the latest developments and advancements in specific fields of expertise;
    • sources of literature and study guides;
    • directories of professional organizations from across the country (including criteria for the qualifications of specific experts);
    • prosecution policies;
    • teaching aids.
      This applies to all Web-based models permitting online access to the data and regular updating of information to maintain currency.
  3. Prosecutors should not shy away from the use of and reliance on novel scientific technique or theory in the appropriate situation, providing there is a sufficient foundation to establish the reliability and necessity of these opinions and that the probative value does not exceed the potential prejudicial effects.
  4. Prosecutors should be reminded of the existence of Section 657.3 of the Criminal Code which sets out the requirements and reciprocal obligations of disclosure imposed on all parties to a proceeding intending to tender expert evidence at trial.

III. Canadian Commissions of Inquiry Since 2005

As identified in the 2005 Report, some of the primary focuses of the Morin and Sophonow Inquiries included the mishandling and improper testing of forensic evidence, reliance on unreliable scientific data, and tainted expert opinion testimony. These issues remain at the core of the controversies surrounding the use of forensic evidence and expert testimony today.

Since the 2005 Report, there have been a number of inquiries that have considered issues in relation to forensic evidence and expert testimony:

a) The Lamer Commission of Inquiry Pertaining to the Cases of: Ronald Dalton, Gregory Parsons, Randy Druken (2006)

This Inquiry examined the criminal justice system’s response to three discredited murder convictions. A number of the 45 recommendations pertain to the Royal Newfoundland Constabulary (RNC), made in response to the serious shortcomings with police investigations into two of the three cases.

Recommendation #6:
(a) The RNC should establish a policy and protocol to assist officers in obtaining independent expertise.Footnote 284

Although there are issues with respect to the scientific validity of polygraph evidence and Supreme Court of Canada has ruled it inadmissible at trial, some of the recommendations highlight the frailties associated with the procedures regarding its use as a forensic tool.Footnote 285

b) Report of the Commission of Inquiry into Certain Aspects of the Trial and Conviction of James Driskell (2007)

One part of this Inquiry focused on the hair microscopy evidence at Mr. Driskell’s trial and the systemic issues arising out of this evidence. Commissioner LeSage heard from panelists with expertise in forensic science and laboratory management and oversight issues, before ultimately making the following comments and recommendations in relation to this issue:

I therefore recommend that microscopic hair comparison evidence should be received with great caution and, when received, jurors should be warned of the inherent frailties of such evidence. As with any evidence, judges must scrutinize the proposed evidence and weigh its probative value against its prejudicial effect...Footnote 286

I am concerned that the problems identified relating to hair microscopy evidence in Driskell’s case are not unique to his case or unique to Manitoba. I accept that a more extensive review of cases from across the country would be advisable, and encourage the Attorneys General of the Provinces and Territories to work together to examine how a case review similar to that conducted in Manitoba might be performed on a national level, and consider the appropriate parameter of such a review.Footnote 287

c) Inquiry into Pediatric Forensic Pathology in Ontario (2008)

Commissioner Goudge made 169 detailed recommendations that aim to restore and enhance public confidence in pediatric forensic pathology and its future use in the criminal justice system. A number of the recommendations focus on education, training, and oversight of the forensic pathologist and his/her role within the criminal justice system. Others focus on the roles of the police, Crowns, and courts as they contend with the intersection of forensic pathology and the criminal justice system.Footnote 288 Those most essential to justice system participants fall into the following categories and are discussed in detail within these chapters:

IV. International Developments

Canada is not alone in examining the interplay between forensic science and its legal system. Much work has been done in the United Kingdom and is underway in the United States aimed at improving the forensic science disciplines to reduce the risk of wrongful convictions and wrongful exonerations, among other issues.

In the United Kingdom, a number of cases over the last few decades have brought to the fore numerous issues relating to weaknesses within the forensic science community and its interface with the criminal justice system. The Home Office recognized the need for a central authority to establish common quality standards in the provision of forensic science services to the police and to the wider criminal justice system. Since 2007, this function has been discharged by the newly created Forensic Science Regulator, operating within the Home Office and accountable to the Home Secretary: “By establishing, and enforcing, quality standards for forensic science used in the investigation and prosecution of crime, the Regulator will reduce the risk of quality failings impeding or preventing the identification, prosecution and conviction of offenders. This will contribute to the Home Office objective of preventing, detecting and deterring crime and improving public confidence in the police and other CJS agencies.”Footnote 289 The Regulator is advised and supported by the Forensic Science Advisory Council (FSAC), a multi-disciplinary group that includes, among others, professionals within the forensic science community, a member of the judiciary, crown prosecutors, defence counsel, and the police.

In the United States at the request of Congress, the National Research Council established the “Committee on Identifying the Needs of the Forensic Sciences Community.” The Committee publicly released its report, Strengthening Forensic Science in the United States: A Path Forward, in February 2009.Footnote 290 As noted by The Honorable Harry T. EdwardsFootnote 291 in his statement before the U.S. Senate upon release of the Report, the multi-disciplinary committee examined the “complex maze” of science, law, and policy issues and concluded that a “massive overhaul” of the forensic science system in the United States was necessary, both to improve the scientific research supporting the disciplines and to improve the practices of the forensic science community. Among its recommendations, the Committee urged Congress to create and fund a new and independent federal agency, the National Institute for Forensic Science (NIFS), to support and oversee the forensic science community.

Concurrent Evidence

An international development that deserves specific mention is the use of concurrent evidence in the courtroom. The presentation of concurrent evidence, colloquially known as “hot-tubbing, has become an established practice in Australian courts and arbitration proceedings and is quickly gaining acceptance in Canada, the United Kingdom and, to a lesser degree, the United States. “Hot-tubbing” solicits the viewpoints of multiple experts at the same time, which can be of great assistance to all justice participants in identifying both key issues and common ground among the experts in cases that involve unusually complex technical issues.

The concept involves expert witnesses testifying together on a panel before a court or tribunal. The court or tribunal effectively chairs a discussion between them, asking questions and seeking clarification of the issues, followed by questions from counsel. The process allows the experts to challenge each other’s evidence directly and helps ensure the experts provide honest, measured and complete pronouncements.Footnote 292

The concept of presenting concurrent evidence or “hot-tubbing” was developed as a means to address three main concerns identified by the judiciary in Australia: the prevalence of adversarial bias or partisanship among expert witnesses, lengthy court proceedings, and the resulting associated costs. Initially, the process was used intermittently in tribunals and, on occasion, in the Federal Court of Australia. It gained acceptance as a method that was able to reduce some of the problems associated with traditional adversarial methods regarding the testimony of expert witnesses, while effectively reducing hearing time.Footnote 293 The practice has since been formally adopted in the Federal Court of Australia,Footnote 294 the Administrative Appeals Tribunal, the Supreme Courts of New South Wales and the Australian Capital Territory, the Land and Environment Court of New South Wales, and some superior courts of New Zealand.Footnote 295 Many Australian courts also require experts to meet prior to trial to try to narrow and resolve issues, to identify the extent of their agreements/disagreements and, often, to commit their positions to writing in a joint report they are required to endorse.Footnote 296

Justice participants in both Canada and the United Kingdom share the concerns identified by the Australian judiciary. Both jurisdictions have pointed to the impact of expert evidence on the length of proceedings and the corresponding cost of litigation to the parties that, in turn, have led to concerns about the accessibility of the court system to litigants with limited means. They also recognize the dangers associated with expert witnesses who misapprehend their role and advocate on behalf of a party.Footnote 297

In the United Kingdom, following a review into the costs of civil litigation in England and Wales, Lord Justice Jackson recommended (among other recommendations) that the procedure of “concurrent” evidence should be piloted in cases where all parties consent and, if the results of the pilot are positive, consideration should be given to amending the civil procedure rules to provide for its use in appropriate cases.Footnote 298 Jackson LJ based his recommendation on the fact that a number of experts, practitioners, and judges expressed to him their support for the use of concurrent evidence in appropriate cases.

In Canada, the Federal Courts Rules relating to expert witnesses were amended in 2010 to address some of these issues.Footnote 299 The stated purpose of the amendments was to provide judges with the necessary tools to ensure that expert evidence is adduced in the most efficient, least costly, and most fair manner. The new rules allow judges to order some or all of the expert witnesses in a case to testify as a panel. The experts are expected to provide their views, and may be directed to comment on the views of other expert panel members as well. On completion of the panel’s testimony, the experts may, with leave of the Court, pose questions to the other panel members, following which the members of the panel may be cross-examined and re-examined in a sequence directed by the Court. The Rules stipulate that an expert witness who is ordered to confer with another expert witness must (a) exercise independent, impartial and objective judgment on the issues addressed; and (b) endeavour to clarify with the other expert witness the positions on which they agree, and the points on which their views differ. The new rules require experts to adhere to a Code of Conduct, which establishes that the overriding duty of an expert witness is to assist the court. The rules also allow the Court to order the experts to confer with each other in advance of the hearing to narrow the issues.

Ontario’s Rules of Civil Procedure also include provisions which came into force on January 1, 2010 that allow judges to order pre-trial “hot-tub” meetings between the experts to identify areas of agreement and disagreement and to prepare a joint statement.Footnote 300

The process of experts testifying together in the “hot-tub” is intended to make their evidence more accessible, less adversarial and, ultimately, more useful to the trier of fact. Advantages include the potential to save court time and associated costs, as well as the likelihood that the expert will provide an honest opinion before colleagues. Misleading answers, confusing positions or uncertainties can be clarified immediately. There are perceived disadvantages as well, including a widespread concern of loss of control, and a fear that one’s expert may make concessions in a group they would not otherwise make. At present, the concept of “hot-tubbing” is not a staple in criminal trials. As noted by Jackson LJ in his Final Report, it remains to be seen which types of cases respond well to the concurrent evidence approach, what costs are saved, and whether the parties involved perceive the process as enabling each side’s case to be properly considered. There is little doubt, however, that successfully soliciting the viewpoints of multiple expert witnesses at the same time by allowing them to discuss complex, difficult issues together can be very useful for any trier of fact.

V. Legal Developments and Commentary

A) Caselaw

“Despite justifiable misgivings, expert opinion evidence is, of necessity, a mainstay in the litigation process. Put bluntly, many cases, including very serious criminal cases, could not be tried without expert opinion evidence. The judicial challenge is to properly control the admissibility of expert opinion evidence, the manner in which it is presented to the jury and the use that the jury makes of that evidence.”Footnote 301

The 2005 Report discussed the Supreme Court of Canada’s decision in R. v. Mohan,Footnote 302 which continues to be relied on for its four-part test regarding the admission of proposed expert evidence. Also reviewed were the Supreme Court’s decisions in J.-L.J. and D.D.Footnote 303 Since the 2005 Report, there have been several other decisions related to expert evidence.

R. v. TrochymFootnote 304

In R. v. Trochym, the accused was convicted by judge and jury of the second degree murder of his former girlfriend. One of the issues was the admissibility of a neighbour’s recollection of the accused at the deceased’s apartment at the relevant time. The neighbour originally told police she had seen the accused at the apartment on Thursday (the day after the murder). After undergoing hypnosis at the request of the police, the neighbour stated she had seen the accused at the apartment on the Wednesday afternoon (day of the murder). Ultimately, her testimony at trial was the result of post-hypnosis evidence.

In determining the admissibility of the post-hypnosis evidence, the Supreme Court of Canada expanded the framework it established in J.-L.J. for assessing scientific opinions to include scientific techniques, and reiterated the importance of reliability as an essential component of admissibility to be determined by the judge as gatekeeper:[O]nly scientific opinions based on a reliable foundation are put to the trier of fact (J.-L.J., at para. 33), and the same principle applies to scientific techniques…post-hypnosis memories must be demonstrated to be sufficiently reliable before being put to the trier of fact. The `gatekeeper function’ of the courts referred to in J.-L.J. (at para. 1) is thus as important when facts extracted through the use of a scientific technique are put to the jury as when an opinion is put to the jury through an expert who bases his or her conclusions on a scientific technique.”Footnote 305

The Supreme Court appreciated the fact that “the scientific community continues to challenge and improve upon its existing base of knowledge. As a result, the admissibility of scientific evidence is not frozen in time.”Footnote 306 Therefore, “even if it has received judicial recognition in the past, a technique or science whose underlying assumptions are challenged should not be admitted in evidence without first confirming the validity of those assumptions:”Footnote 307

While some forms of scientific evidence become more reliable over time, others may become less so as further studies reveal concerns. Thus, a technique that was once admissible may subsequently be found to be inadmissible…

Since Clark, this Court has had the opportunity to consider the admission of novel science in courtrooms. In J.-L.J., it built on Mohan to develop the test governing the admissibility of such evidence. Under this test, a party wishing to rely on novel scientific evidence must first establish that the underlying science is sufficiently reliable to be admitted in a court of law. This is particularly important where, as here, an accused person’s liberty is at stake. Even though the use of expert testimony was not in itself at issue in the present case – this appeal concerns the application of a scientific technique to the testimony of a lay witness – the threshold reliability of the technique, and its impact on the testimony, remains crucial to the fairness of the trial.Footnote 308

As expressed by Commissioner Goudge in his Report, the Supreme Court’s approach above “is consistent with both the evolving nature of science and the responsibility of the trial judge as gatekeeper to exclude expert evidence that is insufficiently reliable. The justice system should place a premium on the reliability of expert evidence if it is to maximize the contribution of that evidence to the truth-seeking function and be faithful to the fundamental fairness required of the criminal process.”Footnote 309

Reference re: TruscottFootnote 310

On June 9, 1959, 14-year-old Steven Truscott was seen riding with his 12-year-old classmate Lynne Harper on his bicycle. Later that evening, Ms. Harper’s father reported her missing. Two days later, her body was found in a wooded area; she had been sexually assaulted and strangled. The following day, Steven Truscott was charged with her murder. He was convicted by a jury on September 30, 1959 and sentenced to death by hanging as required by the Criminal Code at the time. In 1960, his appeal to the Ontario Court of Appeal was dismissed unanimously, following which the Governor General in Council ordered that his death sentence be commuted to life imprisonment. His application for leave to appeal his conviction to the Supreme Court of Canada in 1960 was dismissed.

Mr. Truscott was released on parole in 1969. In November 2001, he applied to the federal Minister of Justice under section 690 (now section 696.1) of the Criminal Code to review his conviction to determine whether there was a reasonable basis to conclude that a miscarriage of justice likely occurred. He argued that numerous documents in existence in 1959 that undermined the Crown’s theory of the case were not disclosed to the defence, and that there was fresh evidence (apart from the undisclosed documents) that undermined the reliability of the medical evidence against him.

The fresh evidence included, among other things, the evidence of experts in pathology, gastroenterology, and entomology. In 2004, the federal Minister of Justice referred this case to the Ontario Court of Appeal.

The Ontario Court of Appeal applied an “evidence-based” reliability test to two well-established scientific disciplines, forensic pathology and entomology.

The Court in Truscott noted the need for courts to cautiously apply threshold standards of admissibility to proposed expert evidence. Scientific opinions not grounded in research may not meet Mohan standards. Commissioner Goudge in his Report commented on this aspect of the Truscott reference: “[I]n my view, the jurisprudences is clear that exclusion of such expert opinions on this basis may be required to avoid the danger of a jury simply accepting expert evidence of a ‘witness of impressive antecedents’ as ‘virtually infallible and as having more weight than it deserves’.”Footnote 311

R. v. ChalmersFootnote 312

In R. v. Chalmers, the accused appealed his conviction for the second degree murder of his wife, who died in 1986. The police originally concluded that she died as a result of an accidental fall from her horse. In 2001, the original investigating officer came across photos of the deceased that “piqued the curiosity” of one of his colleagues and the case was re-opened as a homicide investigation.

On appeal, the accused sought to introduce fresh evidence consisting of a report prepared by a professor emeritus in kinesiology. The appellant attempted to have the professor qualified to provide expert opinion evidence about the movement of horses and people, and about the mechanisms of how a person may fall off a horse and sustain injuries by striking the ground. Relying on the test for admission of expert evidence as articulated by the Supreme Court in Mohan, and refined in relation to “novel science” in L.-J.L. and Trochym, the Ontario Court of Appeal concluded that the professor’s evidence, even if it had been tendered at trial, would not have been admissible.Footnote 313 The Court’s analysis revealed that “forensic kinesiology” was not a recognized sub-discipline of kinesiology, and the professor’s knowledge was based solely on his practical experience gained over 25 years ago while filming his wife’s riding activities, together with the fact that he and his wife stabled her horse for many years.Footnote 314 Therefore, the professor was not a properly qualified expert, and the innovative scientific theory and technique he advanced did not survive the “special scrutiny” required of novel science in order to ensure its reliability.Footnote 315

R. v. BaptistaFootnote 316

The accused, unhappy with his city councillor, wrote a poem expressing his sentiments and posted it on five mail and newspaper boxes. The contents were interpreted as threatening and the accused was charged with uttering a death threat. The Ontario Court of Appeal set aside the conviction and entered an acquittal on the basis that the words in the poem did not meet the legal definition of a threat.

One issue raised on appeal was whether the trial judge erred in excluding the expert opinion proposed by the defence to provide an academic understanding of satire on the basis that without it the trial judge could not understand a reasonable person’s view of the meaning and intent of the poem. The Court held that given the trial judge correctly set out the test identified in Mohan, it was open to the trial judge to conclude the expert opinion was not necessary to assist him in this case.Footnote 317

In a subsequent case, the Court of Appeal referred to the Baptista decision for the proposition that expert opinion evidence that brings no added benefit to the process will be excluded.Footnote 318

R. v. BonisteelFootnote 319

In this case, the defence proposed to call at trial a psychologist to provide expert opinion evidence on false confessions. The expert’s opinion was based on a review of the relevant literature and did not deal with the specifics of the case. The trial judge ruled that the expert evidence was inadmissible because it was not necessary.

The British Columbia Court of Appeal agreed with the trial judge’s finding that the proposed expert evidence was not necessary, given that it did not deal with the specific nature of the evidence in the case, but only with matters about which jury members could form their own judgments based on their own experiences.Footnote 320

This case has been referred to since by the Ontario Court of Appeal as standing for the proposition that “where the proffered opinion evidence falls somewhere between the essential and the unhelpful… the trial judge will have regard to other facets of the trial process – such as the jury instruction – that may provide the jury with the tools necessary to adjudicate properly on the fact in issue without the assistance of expert evidence.”Footnote 321

G.(P.)Footnote 322

The accused was convicted by a jury of sexual offences against his four-year-old daughter. The daughter had been placed in foster care for unrelated reasons and disclosed to her foster parents that the appellant had sexually assaulted her. The Crown sought to introduce the complainant’s statements to the foster parents as proof of the truth of their contents. The Crown expert testified (a) that the complainant should not testify, and (b) that it was his expert opinion that she had been sexually abused - an opinion based on his acceptance of the veracity of the foster parents’ reports to the CAS.

The Ontario Court of Appeal found that the expert (who testified before the jury) strayed outside the boundaries of permissible expert testimony by indicating he believed the out- of-court statements of the complainant and the foster parents. Specifically, the expert’s opinions were not properly elicited – because he treated his factual premise as established fact, the effect of his evidence was to provide his views regarding the veracity of the complainant and the foster parents.Footnote 323

The Court concluded that the trial judge erred by permitting the expert “to indicate a clear and impermissible view of the veracity of other witnesses.”Footnote 324 It held that this result could have been avoided if the expert’s testimony had been elicited by hypothetical questions that incorporated all of the factual premises upon which his opinion was based. If this had been done, the jury would have been left with the task of deciding whether or not to believe the foster parents’ reports of the circumstances.Footnote 325

R. v. AbbeyFootnote 326

In R. v. Abbey, the Crown appealed the accused’s acquittal of the first degree murder of a rival gang member. The issue at trial was identity. At issue on appeal was whether the trial judge erred in excluding an expert’s opinion on the meaning of a teardrop tattoo engraved on the accused’s face within months of the murder.

The Court of Appeal’s analysis began with the importance of delineating the scope of the expert’s opinion:

Before deciding admissibility, a trial judge must determine the nature and scope of the proposed expert evidence. In doing so, the trial judge sets not only the boundaries of the proposed expert evidence but also, if necessary, the language in which the expert’s opinion may be proffered so as to minimize any potential harm to the trial process. A cautious delineation of the scope of the proposed expert evidence and strict adherence to those boundaries, if the evidence is admitted, are essential. The case law demonstrates that overreaching by expert witnesses is probably the most common fault leading to reversals on appeal.Footnote 327

The trial Crown had raised two bases on which the trial judge could admit the expert opinion evidence. The Court of Appeal found that, in the first, the trial Crown had urged a connection between the expert’s opinion evidence and the ultimate issue of identification, a connection that “misconceived the true nature of [the expert’s] opinion and the role he could legitimately play in assisting the jury.”Footnote 328 In fact, the expert’s evidence was clear – he could not speak to the reason why the accused placed a teardrop tattoo on his face, but he could speak to the culture within urban street gangs and the potential meanings to be taken from the inscription of this type of tattoo on the face of a member of that culture.

The trial Crown’s proposed secondary use of the expert evidence at trial involved limiting the expert’s evidence “…to the introduction alone of the possible meanings for the tattoo without providing his analysis of the specific meaning attributable to [the accused’s] tattoo.” The Court of Appeal found this secondary use of the expert evidence permissible – it reflected the proper limits of the expert’s opinion because it “did not go directly to the ultimate issue of identity and did not invite the jury to move directly from acceptance of the opinion to a finding of guilt” – as such, it would become “part of a larger evidentiary picture to be evaluated as a whole by the jury.”Footnote 329

The Court suggests a two-step process that distinguishes between the preconditions to admissibility and the trial judge’s exercise of the “gatekeeper” function, to facilitate the admissibility analysis and application of the Mohan criteria.Footnote 330 Logical relevance, a precondition to admissibility, is distinguished from the broader concept of legal relevance, which is reserved for the “gatekeeper” phase of the admissibility analysis, because it involves a limited weighing of the costs and benefits associated with admitting evidence that has already been shown to be logically relevant.Footnote 331 Ultimately, at the conclusion of a voir dire to determine the above, the trial judge “must identify with exactitude the scope of the proposed opinion that may be admissible.”Footnote 332 In so doing, the trial judge “may admit part of the proffered testimony, modify the nature or scope of the proposed opinion, or edit the language used to frame that opinion.”Footnote 333

New Trend – Back to the Basics

The trial judge’s role as gatekeeper has been a part of Canadian jurisprudence for years. Perhaps the scrutiny necessary to perform that function has effectively diminished because of the belief that forensic evidence, like all other evidence, will be accorded the appropriate weight at the end of the day. As a result, in many cases forensic evidence and expert testimony has not been scrutinized to the level expected before the evidence is heard by the trier(s) of fact.

Following the decision in Trochym where the Supreme Court of Canada reiterated basic principles regarding the acceptance and admission of experts and forensic evidence, and the Goudge Inquiry where the evidence exposed the fact that the “expert” witness and his testimony were admitted time and again based on his reputation only, trial judges will likely approach their task as gatekeeper with greater understanding and scrutiny.

For example, in the recent case of R. v. Teepell,Footnote 334 the trial judge took care to craft a decision to reveal her analysis regarding the proffered expert opinion evidence. In the case, the accused was charged with sexually assaulting a young girl at a party at which both consumed alcohol. The complainant testified that she was intoxicated and fell asleep. The accused maintained he had no memory of these events, and that he had experienced an episode of “sexsomnia” (described as sexual behaviour during sleep).Footnote 335

The trial judge began her analysis by restating Commissioner Goudge’s recommendations regarding the trial judge’s burden of “being the ultimate gatekeeper in protecting the system from unreliable expert evidence.” She dealt with the admissibility of the novel science of “sexsomnia,” as well as the evidence of the experts who testified about it, in a manner that demonstrated an understanding of her role as gatekeeper. She scrutinized the proffered opinion and the science upon which it was based, and concluded that it was of no scientific value and had no evidentiary foundation because it included assumptions and speculation, was without a scientific basis, and was outside the expert’s area of expertise. “The juxtaposition of the testimony of the two sleep disorder experts demonstrates the extent to which this area is, indeed, a ‘ science.’ It also underscores the importance of carefully scrutinizing the reliability of opinions based on novel science and/or the novel application of a clinical technique in a forensic setting.”Footnote 336

Detailed analytical reasons, while not required in law, demonstrate the reasoning process employed by the trial judge to reach his or her conclusion, in keeping with the role as gatekeeper.

B) Commentary

Linking the world of forensic evidence and experts to the courtroom in a way that works for both disciplines has become an increasingly complicated task over the years. Some of the contemporary issues concerning the intersection of forensic science and the law are addressed below.

Evidence-Based Culture

Over the last decade, the global movement towards an evidence-based culture in the forensic sciences has gained momentum in Canada. This approach compels the expert to clearly and accurately identify both the relevant empirical evidence relied on to support the opinion, and the reasoning process that led to the expert’s ultimate conclusion. Incorrect assumptions and other problematic issues become apparent when the reasons behind the opinion are stated clearly. This approach also helps the expert identify and clarify his or her level of confidence in the opinion.

As noted by Commissioner Goudge, the evidence-based culture works to avoid “confirmation bias” – a pitfall closely related to “tunnel vision” that occurs when the expert (or anyone else) seeks out evidence to confirm his or her opinion, and excludes other possible opinions or theories. Evidence-based opinions identify both supporting and contradicting critical evidence. Ultimately, an evidence-based culture will greatly assist the role of the court in protecting the legal system from the effects of improper or flawed scientific evidence.Footnote 337

Judicial Gatekeeping Function

The evidence at the Goudge Inquiry demonstrated the vulnerability of the Canadian legal system to unreliable and flawed expert evidence. One of the issues Commissioner Goudge addressed in relation to this concern was the judge’s role as gatekeeper to ensure that expert evidence is sufficiently reliable to be admitted as evidence. A number of recommendations have been made to help address these concerns and have been referred to above.

Of critical importance is the need for the judge to define precisely the nature of, and the limits of, the expert witness’ expertise at the outset of each trial. Without doing so, the opportunity exists for expert witnesses to stray from their expertise:

This description [of the nature and limits of expertise] gives clarity to what the experts can properly opine on and allows the court to curtail the “roaming expert”

The challenge of roaming expert witnesses for the criminal justice system is substantial. All the admissibility safeguards…to ensure the relevance, necessity, and reliability of expert scientific evidence are for naught if experts are allowed to stray beyond their field of expertise and offer, under the guise of expertise, what are, in essence, only lay opinions that have no scientific value.Footnote 338

While Commissioner Goudge made a number of recommendations related to the trial judge’s gatekeeping function, he also strenuously advised that all participants in the justice system share the important role in ensuring that only properly qualified witnesses, with relevant, necessary evidence, provide expert opinion evidence with neither more nor less than their legitimate force and effect.

Jury Instructions with Respect to Expert Evidence

The Canadian Judicial Council has published the following model jury instructions on expert opinion evidence (general):

You heard the evidence of NOW,Footnote 339 an expert witness. S/he gave an opinion about some technical matters that you may have to consider in deciding this case. S/he is qualified by his/her training, education and experience to give an expert opinion.

Remember, the opinions of experts are just like the testimony of any other witnesses. Just because an expert has given an opinion does not require you to accept it. You may give the opinion as much or as little weight as you think it deserves. You should consider the expert’s education, training and experience, the reasons given for the opinion, the suitability of the methods used and the rest of the evidence in the case when you decide how much or little to rely on the opinion. It is up to you to decide.

NOW was asked to assume certain facts. What an expert assumes or relies on as a fact for the purpose of offering his or her opinion may be the same or different from what you find as facts from the evidence introduced in this case.

How much or little you rely on the expert’s opinion is up to you. But the closer the facts assumed or relied on by the expert are to the facts as you find them to be, the more helpful the expert’s opinions may be to you. How much or little you rely on the expert’s opinion is entirely up to you. To the extent the expert relies on facts that you do not find supported by the evidence, you may find the expert’s opinion less helpful.Footnote 340

Effective Communication

A lack of effective communication between the expert and the criminal justice system is problematic. Recent inquiries have brought to light the dangers that may occur when expert evidence is communicated in ways that promote misinterpretation or misunderstanding on the parts of police, prosecutors, defence counsel and the courts.

Commissioner Goudge emphasized that expert witnesses are called to serve the justice system, and to be effective in this role they must be able to communicate their opinions very clearly:

… it is important to remember that the main purpose of forensic pathology is to serve the justice system. When the opinions of forensic pathologists, including their limitations, are not properly understood, the justice system operates on misinformation. This breakdown in communication may have serious and sometimes disastrous consequences for the administration of justice and those most affected by it, including accused persons and families of the deceased. The innocent should not be charged or convicted, or the guilty go free, on the basis of expert opinions that are misunderstood.Footnote 341

Although these references focus on forensic pathologists, the premise applies equally to all expert witnesses – effective communication is of the utmost importance in the expert’s role to assist the administration of justice.

A related issue is how, and the extent to which, an expert witness communicates his or her level of confidence or certainty in his or her opinion. Our criminal justice system demands certainty and often pushes expert witnesses to communicate their level of certainty. As noted by Commissioner Goudge, “…of greatest concern is the possibility that the criminal justice system, in its search for certainty, will interpret a pathology opinion as reflecting a higher level of confidence than the expert intended.”Footnote 342 Indeed, if not recognized, this issue can lead to wrongful convictions based on misinterpreted expert witness opinions.

Yet another issue involves misplaced reliance on non-pathology information that can lead to bias. Often the extent of this reliance is not readily apparent in either written or verbal accounts of the expert’s opinion. Furthermore, the reliance by experts on circumstantial evidence is itself a controversial area. Commissioner Goudge has included a number of recommendations to help guard against this potential bias.Footnote 343

A similar issue relates to reliance by experts on other expert opinions. Expert witnesses should be encouraged to consult with fellow colleagues and other experts – the caveat is to ensure that all such consultations are documented.Footnote 344


Testifying is a significant aspect of the duties of many experts. It is obvious to those familiar with the criminal justice system that triers of fact are easily impressed with the credentials of most experts. Much literature has been devoted to the “aura of infallibility” that accompanies the expert in the witness stand.

It is very important that expert witnesses fully understand the culture they represent, a task best achieved through ongoing education. It is also important for those involved in the criminal justice system to remain cognizant of, and understand, this culture. Joint continuing education seminars can address the concerns associated with expert witnesses, and better prepare Crown Attorneys, defence lawyers, and police to understand the potentially problematic dynamics associated with expert witnesses. The goal is to improve communication between experts and others involved in the justice system – during the processes that lead to a trial, during trial preparation, and during testimony. An example of a successful joint educational opportunity was the “Pediatric Head Injury and the Law” conference hosted by the Ministry of the Attorney General in Ontario in March, 2010. Crown attorneys, defence counsel, members of the judiciary and pathologists attended to focus on issues related to pediatric forensic pathology and wrongful convictions.

Particularly encouraging is the recent creation of the Centre for Forensic Science and Medicine at the University of Toronto, an interdisciplinary initiative dedicated to advancing teaching and research in the forensic disciplines. Of particular importance to the Centre is recognition of the interface between the law and the social sciences. As well as offering inter-professional education for students of medicine and law, the Centre offers continuing professional development initiatives for the medical and legal communities, and intends to facilitate research into areas of controversy and debate in forensic medicine and science, among other educational endeavours. The Centre is currently developing symposia and workshops for continuing professional development for lawyers and the judiciary.

As observed by Commissioner Goudge, the more interaction there is between these groups, the more each will develop a common understanding of each other’s roles and limitations, which will surely serve to improve the administration of justice.Footnote 345

C) Prosecution Services Response to Driskell Inquiry Recommendation on Hair Microscopy Case Review:

In the 2007 Driskell Inquiry Report, Commissioner LeSage made the following recommendation:

I am concerned that the problems relating to hair microscopy evidence in Driskell’s case are not unique to his case or unique to Manitoba. I accept that a more extensive review of cases from the across the country would be advisable, and encourage the Attorneys General of the Provinces and Territories to work together to examine how a case review similar to that conducted in Manitoba might be performed on a national level, and consider the appropriate parameters of such a review.Footnote 346

Since then, all Canadian jurisdictions have conducted reviews in different forms. The most formal were in Ontario and British Columbia.

In B.C., the review, under the supervision of Regional Crown Counsel Oleh S. Kuzma, QC, examined all cases of culpable homicide, sexual assault, robbery and other indictable offences including the use or attempted use of violence that fit within the following parameters:

The reviewers considered whether there was a reasonable basis to believe that, by virtue of this evidence, a miscarriage of justice has taken place. In mid-December 2009, the Advisory Committee appointed by the Assistant Deputy Attorney General submitted its report. The committee consisted of a retired Justice of the Supreme Court and Court of Appeal of British Columbia, a defence counsel nominated by the UBC Law Innocence Project, a Deputy Chief of the Vancouver Police Department and Mr. Kuzma. After preliminary screening, the committee reviewed two homicide and two sexual assault cases. It unanimously concluded that there was no reasonable basis to believe that, by virtue of the hair microscopy evidence, a miscarriage of justice has taken place in the convictions against the four individual accused persons.

In Ontario, a preliminary search was conducted of forensic lab databases (RCMP and Center of Forensic Sciences) and police and prosecution files in which hair samples were gathered. The review considered murder and manslaughter convictions from 1985 to 2000. In each case, the evidence was reviewed to determine whether hair comparison evidence was used and played a significant part in the decision in an individual case.

The Ontario Criminal Conviction Review Committee, with advice from The Honourable Patrick LeSage, oversaw the review. Criteria and an implementation plan for the review were developed. The review was conducted in two phases. A small working group of counsel completed the initial two phases of the review by firstly applying the following criteria to determine whether further review of individual cases was warranted:

  1. the case occurred during the 15 year time frame between 1985 and 2000;
  2. the conviction was for culpable homicide;
  3. the accused pled not guilty and asserted factual innocence;
  4. the accused appealed to the Ontario Court of Appeal and the appeal was dismissed;
  5. hair evidence was tendered at trial; and
  6. hair is available for testing.

Cases which met the criteria in phase 1 were subject to further review in phase 2 to determine the importance of the hair evidence to the conviction in the case. The OCCRC is now reviewing the cases to determine whether there is a reasonable basis to conclude that a miscarriage of justice may have occurred in any of the cases. If any case raises a concern on this basis, it will be referred for mitochondrial DNA testing.

Other jurisdictions consulted Crown counsel in a less formal way. Most jurisdictions reported that their reviews did not reveal any cases in which microscopic hair comparison evidence was used or played a factor in the conviction.Footnote 347

VI. Potential Pitfalls to Avoid

The Goudge Inquiry highlighted the ten most egregious ways in which Charles Smith, the pathologist at the heart of the Inquiry, failed in his role as an expert witness. These reflect common pitfalls that must be avoided by the expert witness and, in turn, illustrate what others involved in the criminal justice system must be cognizant of to help prevent future miscarriages of justice.

  1. The Expert as Advocate – the expert’s role does not include advocacy on behalf of the party that called the expert; it is to convey his or her scientific findings, his or her opinion, and the level of certainty to which he or she holds the opinion.Footnote 348
  2. The Inadequately Prepared Expert“…expert witnesses can be of assistance only when they have a complete understanding of the case and the basis of their expert opinion. They can have such an understanding only with proper preparation.”Footnote 349
  3. The Overstated Expertise of the Expert“When expert witnesses testify, they have a responsibility to make the court aware of the limits of their expertise. A failure to do so prevents the court from fully assessing whether the person should be permitted to give the opinion evidence. Expert witnesses are not expected to be knowledgeable in every substantive area. When they lack knowledge or experience in an area that informs their analysis, they are expected to be candid about it.”Footnote 350
  4. The Expert and Unscientific Evidence“Expert witnesses are retained to provide opinions because they are experts in a particular area. While reference to personal anecdotal evidence might assist the court in understanding a particular point, it should not form the basis of the opinion on a particular matter.”Footnote 351
  5. The Expert and Unbalanced Evidence“An expert must ensure that the controversies in the discipline are understood by the trier of fact.” Providing an opinion based on his or her interpretation of the scientific findings and the literature is not enough. “This approach makes a proper assessment of the opinion very difficult and leaves the criminal justice system ill served.”Footnote 352
  6. The Expert’s Attacks on Colleagues“Although an expert may criticize the work of another expert, a reason must be given for the criticism.” Disparaging, arrogant, unjustified and uncharitable remarks are “unprofessional and entirely unhelpful to the court.”Footnote 353
  7. The Expert and Evidence Beyond His Expertise“Expert witnesses are called to the court to speak to the issues that involve their expertise. They are not given free rein to discuss other matters on which they happen to have an opinion.”“Experts have a positive obligation to identify and observe the limits of their particular area of expertise… They should not offer any opinions outside their specialty and, when testifying, should clearly state when particular questions or issues fall outside their expertise.”“Although experts must always recognize the limits of their expertise and stay within those limits, judges and counsel also play an important role in ensuring that those boundaries are respected.”Footnote 354
  8. The Speculating Expert – “[Experts] provide [scientific] opinions. I do not see how [experts] can believe that, when there is no [scientific] evidence, it is open to them to speculate on what could have happened. Although I appreciate that [experts] want to be helpful to the court, speculating about the various possibilities without any [scientific] evidence is unhelpful and potentially prejudicial. I also accept that the court and counsel have a duty to ensure that the [expert] does not give inappropriate evidence. When the court or counsel realizes that the [expert] is speculating, either one should object and put an end to that line of questioning. [Experts], however, are in the best position to ensure that the evidence that they provide is not speculative and is substantiated by the necessary evidence. The [expert] must be responsible for doing just that.”Footnote 355
  9. The Expert and Casual Language“Expert witnesses’ use of language is an important part of their role. How the expert communicates an expert opinion to the court affects how the court will perceive and weigh the opinion.” For example, at times Dr. Smith attempted to “convey technical concepts in non-technical terminology that resulted in an appearance of casualness that was inappropriate in the circumstances…although I understand that it can be very difficult for experts to express the degree of certainty with which they hold their opinions, it is unscientific and inappropriately inexact for an expert witness to use betting terminology. In many of these instances, the language masked the real problem with the testimony – it was speculative.”Footnote 356
  10. The Expert Who Misleads“It goes without saying that an expert witness giving evidence under oath should do so with complete candour and honesty. False and misleading statements should form no part of an expert witness’s evidence.”Footnote 357

Avoiding these pitfalls will go a long way to assisting all participants in the criminal justice system throughout the entire process – from the moment the expert is engaged, until the final disposition of the case. For example, it is expected today that expert witnesses will acknowledge existing controversies within their realm of expertise or science. The importance of communicating the existence of controversial issues is vital at each stage of an investigation and prosecution, as explained by Commissioner Goudge:

…this approach enables the police to make fully informed decisions about the direction of their investigation, the need for additional expertise, and the existence of reasonable and probable grounds. It permits prosecutors to make informed evaluations about the reasonable prospects of conviction. When charges are laid, this context educates the defence and makes an informed and independent assessment of the strength of the Crown’s case more likely. Ultimately, this information is clearly relevant for the judge or the jury as they try to understand and evaluate the quality of the positions of the Crown and the defence. In those cases where the [expert] expresses an opinion as well as the context of the relevant controversy, the judge or the jury is better able to appreciate where the opinion falls within a spectrum of views in the forensic pathology community and, therefore, to evaluate it properly. Without this context, misunderstandings can easily arise.Footnote 358

VII. Status of Recommendations

In light of increasingly complex prosecutions, growing caseloads, and constraints on time and resources, it is difficult today for participants in the criminal justice system to keep abreast of significant forensic developments, especially when new or novel areas of expertise arise. Education seminars conducted by a variety of experts and incorporated into regular and ongoing education sessions will best assist police and prosecutors in their cases. This type of intensive training will provide insight into the various forensic disciplines and acquaint prosecutors and police with new developments and procedures.

Of great benefit is an inter-disciplinary approach to education among the bar, the judiciary, and the forensic science disciplines. This approach has been used in other areas of the law with great success. In the area of forensic evidence and expert testimony in particular, an inter-disciplinary approach will work to the advantage of all participants, will facilitate the trial process in complex cases and, invariably, will assist the administration of justice.

As recommended in the 2005 Report, the Subcommittee considered the feasibility of establishing a national central repository to catalog and track case law, newsletters and articles, the latest developments and advancements in specific fields of expertise and the like. Although a central repository has not been created, the Subcommittee functions as a conduit for the exchange of this sort of information among all prosecution services and police agencies represented on it. The federal government has taken the lead in ensuring a fulsome exchange of information takes place, not only on forensic information, but on all issues related to wrongful convictions. It will continue in this role.

VIII. Additional Recommendations

The Subcommittee makes the following additional recommendations:

  1. Continuing multi-disciplinary legal education among the bar, the judiciary, and the scientific disciplines and police is of utmost importance and will assist all participants in becoming literate with respect to basic scientific concepts, developing scientific areas, methods, and techniques.
  2. There should be continuing education for prosecutors on the proper use of, and how to examine and cross-examine, expert witnesses.
  3. The federal government should continue its role in updating the provinces and territories with current, relevant information in this area, including press releases, reports, etc. This recommendation effectively and efficiently implements recommendation 2 in the 2005 Report.
  4. Each province or territory should encourage an appropriate network, both within the province/ territory and with other provinces/ territories, when searching for expert witnesses for their cases.
  5. Case conferences between Crown experts and defence experts should be encouraged to try to narrow and/or potentially resolve the scientific issues in a given case. Crown and defence counsel should encourage these case conferences and request that issues relevant to the case be addressed.
  6. Some international jurisdictions have rules relating to reciprocal disclosure of expert evidence. The Criminal Code addresses this issue in a limited way. Consideration should be given to strengthening the Criminal Code provisions to provide for reciprocal disclosure well in advance of trial. This greatly enhances a full consideration of scientific issues affecting the soundness of prosecutions and convictions.
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