A recent Canadian case has highlighted an apparent issue that is affecting how some courts are assessing the probative value and admissibility of expert image comparison evidence. This article reviews this recent case in the context of previous rulings and recommends how image comparison evidence should be presented to the court by experts and argued by counsel tendering such evidence to avoid a negative ruling.

Previous articles on this site have highlighted cases wherein Canadian courts have evaluated the probative value and admissibility of expert image comparison evidence (Image Comparison Evidence: The Canadian Experience; Court Restricts Forensic Video Analyst in Image Comparison Opinion Evidence; Canadian Court Restricts Evidence of Forensic Video Analyst in Murder Trial). Among these cases are decisions from British Columbia, Ontario, and Quebec wherein trial judges have disallowed the presentation of expert image comparison evidence by qualified forensic video analysts. As I do not intend to repeat the content of the earlier articles, I recommend reading them to place this article in context.

The Recent Case

R. v. Sprout, 2023 BCPC 124 (British Columbia Provincial Court) is a case that does not involve expert image comparison evidence but is relevant because of obiter comments made by the trial judge about image comparison evidence. The case involved the aggravated assault and robbery of a Walmart security guard and the assault of another security guard and store customers, allegedly perpetrated by the defendant. The detailed facts of the case are not necessary to develop the image comparison issue and I will restrict my factual analysis accordingly.

Due to a power disruption at Walmart, no CCTV of the event was available for download. However, eyewitnesses noted that the offender had tattoos on his arms and cellphone video of the event taken by a witness supported the presence of such tattoos. The defendant was located two hours later near some of the stolen merchandise and the arresting officer took photographs of the tattoos on his arms. The defendant was arrested because the officer believed that the questioned and known tattoo images showed the same tattoos. The sole issue before the court was whether the defendant was the person who committed these offences.

Though expert image comparison evidence regarding the tattoos was not part of the Crown’s case, the Court noted that it would have liked expert assistance in evaluating the questioned and known images. The Court raised two cases (Aitken and Spezzano, discussed in previous articles noted above) with counsel and concluded from those cases that expert image comparison evidence generally was not admissible as it was not necessary for the trier of fact to receive expert assistance. The Court therefore attempted to undertake its own comparison but noted that technical issues made that exercise of very limited value. The Court could not determine whether the scale of the images was comparable, and this made comparing the tattoos difficult. It also noted that comparing two dimensional tattoos to their three-dimensional application on arms was difficult. The Court was therefore uncertain about the accuracy of any comparisons that it undertook. The Court concluded that while the questioned and known tattoos were similar, it could not be said that they were the same.

The Implications of Sprout

Though I cannot determine whether expert image comparison evidence would have been of assistance to the Court, it is highly unlikely that an expert would have reached a conclusive positive identification opinion. While tattoo identification was important in this case, it was not pivotal as there were other identification problems that militated against conviction. The reason why this case is worthy of commentary is that it illustrates a lack of sufficient knowledge by counsel and the Court as to the value of expert image comparison evidence and relevant case law on this important topic.

Counsel must be aware of the existence and value of expert image comparison evidence. No such expert assistance was obtained by the Crown in this case, either because counsel was not aware of its existence or because counsel determined that it would not materially strengthen the Crown’s case. Equally, the defence could have pursued such evidence but did not appear to have done so. In fairness, funding may not have been available to the defence. Secondly, counsel must be aware of the relevant law and advise the court accordingly. In this case, the trial judge was left with the mistaken impression that expert image comparison evidence was not admissible and that the Court had to do the comparison work itself, a task it was ill-equipped to perform. This conclusion was based on a misapprehension of the law in Canada.

There are cases that have been critical of expert image comparison evidence and have either restricted its use or disallowed it altogether. Those cases, which are either fact specific or arguably wrongly decided, are discussed in the above noted articles. None of these cases are appellate level decisions. If trial judges continue to be given ineffective assistance by counsel, there will be more rulings like Sprout wherein judges wrongly conclude that expert image comparison evidence is not admissible.

Making the Case for Expert Image Comparison Evidence

In a case where expert image comparison evidence would be of assistance to counsel in presenting their case and the court in making findings of fact, three steps must be taken to maximize the likelihood of a favourable ruling.

First, the proposed forensic expert must be called to testify in a voir dire. The purpose of this testimony is to educate the court on the complexities involved in the interrogation and interpretation of images generally, the various technical attributes of digital imagery that impact the ability of non-experts to accurately evaluate image content, the scientific methodology that must be utilized when doing comparative work, the experience needed to conduct comparisons, and the time required to meaningfully evaluate images. The expert should then be taken through a thorough direct examination of expert work done in the case before the court. It is only by leading this didactic and case specific evidence that the court can competently assess whether the trier of fact can do this comparative work without expert assistance. I have found this approach helpful when leading such evidence in circumstances where its admissibility was disputed.

Second, after the expert has presented the evidence, counsel must be well versed in arguing why the factors outlined by the expert make competent image comparison by non-experts very difficult. Counsel must also point to those aspects of the expert’s observations and opinions that would not have been made or reached in the absence of the expert.

Third, counsel must engage in a thorough presentation of relevant case law on expert image comparison evidence, pro and con, and argue why the law supports the use of such evidence. Contra cases must be distinguished on their facts or argued as wrongly decided. Appellate authority must be engaged.

A comprehensive evidential presentation and robust legal argument should serve to make a compelling case for the court to consider. While there is no guarantee that the court will decide in favour of counsel presenting the evidence, at least the strongest possible case will have been put on record. That is important for the trial court so that a favourable ruling can be fully justified, and should the evidence be ruled inadmissible, then a proper record will have been created in the event of an appeal.