When only one expert witness is presented at trial, the Court may find it difficult to critically evaluate the expert evidence. If the evidence is not controversial and both sides agree with the findings, this will be a non-issue. However, when the evidence is contentious, a one-sided presentation is more problematic. While skillful cross examination of the expert by opposing counsel can expose weaknesses in methodology and conclusions, lawyers cannot give evidence. They can only challenge and argue the evidence that has been presented by the parties. Therefore, the most effective way to fully evaluate the expert evidence presented by one party in the litigation is by the other party presenting their own expert evidence. This will allow the Court to make a more informed decision.
This article highlights a recent murder prosecution in Canada wherein competing experts proved to be pivotal in the Court’s evaluation of the proffered expert evidence. R. v. Bazuhair and Nirmalendran, 2024 ONSC 1584 (Ontario Superior Court of Justice), was a murder prosecution wherein the defendants were charged with causing the death of the victim by cornering him outside the entrance to his apartment building and opening fire with two firearms. The victim was shot 24 times. The murder was recorded on surveillance video, which showed the killers arriving, carrying out the attack, and leaving. However, their faces could not be seen and there were no witnesses. The central issue at trial was the identification of the killers. The surveillance video evidence was an important part of the prosecution’s case.
As part of his case, the defendant N called an expert in photogrammetry who opined that based upon his measurements of the killers as observed in the video recordings, N could not possibly have been one of the killers because he was significantly shorter than the relevant killer observed on the video recording. The Crown called expert evidence, not for the purpose of coming up with a second height determination, but rather to opine on the reliability of the defence expert’s methodology and conclusions.
The Defence Expert Evidence
The defence expert examined the video files and still images provided to him by defence counsel. One of the video recordings was a compilation video of several surveillance videos. He also attended the scene to determine if there were sufficient location points present at the scene that were also in the video recordings which could be used for measurement purposes. He found that two recordings met these requirements. While at the scene, he took photographs from various angles. He selected video frames where the killers appeared to be at their most upright position and placed an X on the top of their heads. His computer software (PhotoModeler) then drew a vertical line to the ground and measured the height of the men accordingly. The expert stated that his software and camera determined the location of the bottom point.
Using PhotoModeler, the expert opined that the height of the man alleged to be the defendant N was 5’7”, plus or minus an inch. This height took into account the fact that the suspect was wearing shoes. No adjustment was made for the hooded sweatshirt worn by the suspect, stating that it would have a “negligible effect” on the overall height. The defendant N’s actual height was 5’4” with shoes.
The Crown Expert Evidence
When an opposing expert is called, the expert will typically perform the same general task as the other expert and then opine upon their differing results in court. Therefore, it would normally be expected that the Crown expert would have done her own measurements from the video and the scene and would then offer her opinion on suspect height. Interestingly, that is not what occurred in this case. Rather, the Crown expert, a certified forensic video analyst, was called to critique the methodology and results of the defence expert. She was not tendered as an expert in photogrammetry or in the use of PhotoModeler, but rather as an expert in forensic video analysis. It was the Crown expert’s opinion that the defence expert’s height determinations were not reliable because the video recordings were of such limited quality that reliable and accurate measurements could not be obtained from them. Further, she pointed out flaws in the defence expert’s methodology.
The following criticism was presented in testimony:
• The Crown expert noted that the video images were dark and that this impacted the ability to discern the edges of objects, such as footwear. She said that the images should have been brightened to see if the footwear could be made more visible.
• The people shown in the video images were so small that one pixel might equate to 4-5 inches, making measurement accuracy problematic.
• The camera angle was problematic as it looked down at the individuals.
• Lens distortion was present and rounded the edges of the images.
• The defence expert should have used the raw video footage rather than the compilation video as the latter version will not be as clear or have as much data as the raw video.
• The defence expert’s report should have undergone peer review.
• All the measurements used by the defence expert were taken from predictive (P) frames rather than intra (I) frames. This adversely impacted the accuracy of the measurements as the expert was not using images captured by the camera.
As noted above, the Crown expert did not offer a different measurement but rather cast doubt on the reliability of height determination presented by the defence expert.
The Court’s Evaluation of the Expert Evidence
The Court found the evidence of the defence expert to be completely unreliable based on the above noted weaknesses in his methodology. The most significant problem that was flagged was that the expert had very little, if any, experience measuring the height of an individual who was walking. His attribution of a one-inch margin of error had no scientific basis and amounted to little more than a guess. He did not articulate the factors that would affect the margin of error, such as distance from the camera, lack of image clarity, lens distortion, and camera angle. Additionally, there was uncertainty in accurately determining the top of the head of the individuals due to them wearing hoodies and ascertaining the amount of height that was added by footwear.
While some of these faults may be considered minor, cumulatively, they left the Court with a “complete lack of confidence in the accuracy of the measurements”. Additionally, the Court found that the defence expert inflated his credentials in various ways that were troubling and noted that the expert had a financial interest in the software that he used for his work. Finally, the Court was critical as to the quality of the expert’s testimony in court. His testimony lacked clarity, shifted positions over the course of his evidence, and at one point was described as torturous. In sum, the Court found the expert to be an unreliable witness and his evidence was rejected. “He was careless and unscientific in the assessments he carried out and also less than careful in his evidence at trial.”
Commentary
This case is interesting because it illustrates how important it can be in some cases to have a second expert providing evidence in court. Not all experts have the same level of competence and integrity. In the absence of opposing expert evidence, the only method of ferreting out expert evidence shortcomings is through effective cross examination. While that may challenge and weaken expert evidence, it does not constitute opposing evidence – only a second expert witness can provide that tangible content. Opposing counsel, whether prosecution or defence, has a difficult task when cross examining an opposing expert without the benefit of their own expert to provide valuable consultative assistance. In many cases, there may not be second expert to provide this assistance, either through lack of funding or lack of foresight by counsel.
Being qualified as an expert witness by the court does not mean that the expert’s evidence is correct. It only means that the expert has met the threshold to testify in an expert capacity. As seen in this case, the defence expert erred in his methodology and was almost certainly wrong in his conclusions. Experts have a professional responsibility to provide evidence to the court that is scientifically robust and reliable. They must approach their work objectively and impartially because their duty is to the court, not the instructing party. When experts do not achieve these markers, then cross examination and opposing expert evidence is needed to expose methodological and conclusionary errors, as occurred in this case.