Providing an expert opinion on cause and origin in fire litigation is challenging at the best of times as evidentiary issues are an inherent part of these cases. Much of the evidence quite literally goes up in flames during the incident itself. When faced with missing or severely compromised evidence, there are important considerations for plaintiffs, or their insurers, seeking out credible and reliable expert opinion evidence that is of assistance to the Court. The case of Child v CNH America LLC, 2025 ABKB 180 presents a situation where the evidence was not only compromised by the fire itself, but it also became lost, corroded, and faded through the passage of time. This case provides an opportunity to explore some of the important considerations that should influence when and how experts are retained in fire cases.Providing an expert opinion on cause and origin in fire litigation is challenging at the best of times as evidentiary issues are an inherent part of these cases. Much of the evidence quite literally goes up in flames during the incident itself. When faced with missing or severely compromised evidence, there are important considerations for plaintiffs, or their insurers, seeking out credible and reliable expert opinion evidence that is of assistance to the Court. The case of Child v CNH America LLC, 2025 ABKB 180 presents a situation where the evidence was not only compromised by the fire itself, but it also became lost, corroded, and faded through the passage of time. This case provides an opportunity to explore some of the important considerations that should influence when and how experts are retained in fire cases.
Background
This case originated with an incident in 2011 where a tractor caught fire while being operated to prepare the spring fields for seeding. The tractor’s cab was quickly engulfed in flames. Fortunately, the farm worker operating the tractor was able to jump away before the heat from the fire caused the fuel tank and tires to explode.
The incident spawned two lawsuits: a personal injury action by the farm worker who was severely injured from his jump, and an action by the farm itself seeking compensation for property damage caused to the tractor. Since the tractor was merely a year and a half old, both the farm owner and the worker claimed that the tractor must have been defective, and that the manufacturer should be held liable for the fire.
In essence, the dispute revolved around an allegedly defective dust guard that was positioned over the driveshaft of the tractor. The farm owner and worker alleged that the dust guard had detached from its weld points so that it was causing friction against the revolving driveshaft of the moving tractor, and sparking the organic debris from the field that was collecting around the articulating joint of the tractor.
Despite the simplicity of the essential dispute, the litigation itself was incredibly complex. Between the three parties involved, seven experts were retained to provide opinions related to the origin and cause of the fire: five expert fire investigators and two expert metallurgists opined on the dust cover welds, all with differing opinions on causation. The complex nature of the expert evidence in this case combined with significant court backlog caused this litigation to drag on for nearly eleven years, with a final decision not being rendered until the spring of 2025.
Rather anticlimactically, and despite having the benefit of seven experts, the Court ultimately ruled that the cause of the fire was undetermined. Most of the experts were able to agree that the fire had originated from somewhere in the area of the tractor’s driveshaft and articulating joint, but the experts were completely divided on the cause of the fire. The inability to find a middle ground on causation was exacerbated by three significant evidentiary issues in this case:
Evidentiary Issue #1 – Effect of Limited Availability of Evidence on Investigation
With regard to the scene investigation, only two expert investigators were retained in time to have the benefit of attending and observing the site of the fire. The remaining experts needed to rely on photographic evidence of the fire scene for their opinions.
With regard to the investigation of the damaged tractor, the evidence was compromised due to removal of the tractor from the location of the fire to a storage facility at the recommendation of one of the expert investigators. The condition of the tractor was not documented throughout the move, and it later became unclear whether the disputed dust guard became fully detached during the move process. Additionally, the storage facility itself was located in a northern city known for unfavourable weather conditions. At the storage facility, the tractor was not tarped or protected from the elements in any way. This caused severe corrosion to the metal of the tractor, undermining the experts’ ability to confidently investigate the metal dust guard and driveshaft.
With regard to the investigation of the component parts of the tractor, the evidence was compromised by the removal of portions of the tractor’s hydraulic system early on in the investigation. In the fall season preceding the fire, the farm’s owners had noted that the tractor required a high volume of replacement hydraulic fluid. This observation led some experts to investigate a potential hydraulic leak causing or contributing to the fire. One of the expert investigators that was retained early on in the investigation was asked to remove portions of the tractor’s hydraulic system for analysis, including certain hydraulic lines and remotes. These pieces of the hydraulic system were subsequently passed off to another investigatory firm and lost. This loss deprived three of the later origin and cause experts of the benefit of observing and analyzing the hydraulic lines, and likely caused the expert analysis to focus more heavily on the allegedly faulty dust cover rather than a potential fault in the hydraulic system.
Evidentiary Issue # 2 – Effect of Limited Availability of Evidence on Testing
The Court found that some of the experts’ opinions were too focused on assessing whether the dust cover was faulty and, thus, the cause of the fire. In particular, two experts designed experiments seeking to prove or disprove that the dust cover was the cause of the fire. The Court found it could not rely on either of these experiments due to the inherent limitations of the evidence that was a foundation for their testing.
In our first example, one origin and cause expert, who did not attend the scene of the incident, and only examined the tractor after it was corroded, attempted to prove that the dust cover caused the fire through friction between the dust cover and the driveshaft of the tractor. This expert formulated an experiment to show that the dust cover would generate heat and sparks by rubbing against the driveshaft. With the singular goal of proving that the dust cover could generate heat or sparks by rubbing against the driveshaft, the expert incorporated elements that would not have been present at the time of the incident into his experiment. For example, to prove his conclusion, the expert went so far as too apply external force to get the dust cover to grind against the driveshaft. The expert was not able to prove to the Court that this type of force would have been present at the time of the fire.
Ultimately, this experiment was of little value to the Court because the judge viewed it as an attempt to prove a hypothesis, and not to replicate the conditions actually present at the time of the incident. Conducting experiments using an exemplar can be a useful method of conveying information to the Court, particularly in fire and arson investigations where much of the actual evidence is destroyed in the fire. However, to be of assistance to the Court, the expert must be able to passably recreate the conditions that would have been present at the time of the fire.
In our second example, a rival origin and cause expert attempted to replicate the first experiment to prove that the dust cover would not grind against the driveshaft, even if the dust cover did become fully detached from the weld points prior to the fire. The problem with this second experiment was that the expert claimed that no significant heat was generated by the loose dust cover without actually using an instrument to measure the temperature of the dust cover during the experiment. During his cross-examination, this expert argued that he knew there was no heat to measure because he had placed his hand on the dust cover at least once during the course of the experiment and felt no warmth. The Court did not accept this form of subjective measurement of temperature as sufficient evidence to support his expert opinion.
Evidentiary Issue #3 – Effect of Limited Availability of Evidence on Testimony at Court
In cases involving evidentiary challenges similar to those present in this case, experts may be limited in the scope of the opinions they can present at trial. However, the Court may still find an expert opinion persuasive in spite of evidentiary issues, if the opinion is presented with the appropriate amount of deference.
The first example we look at is the situation where the expert did not concede the limitations in his opinions due to the limitations in the evidence available to him during his investigation. The mechanical engineer retained by the manufacturer to give an opinion on origin and cause was one of the experts who had to generate a report based on severely compromised evidence. He did not have the benefit of reviewing the lost pieces of the hydraulic system, and, to compound matters, the tractor was severely corroded by the time of his examination.
The compromised nature of the evidence led this expert to conclude in his written report that the cause of the fire was undetermined. He ruled out the dust cover as a cause because there was no evidence to suggest a loose dust cover would cause friction against the driveshaft. He did consider the loose connection on the hydraulic line near the articulating joint to be a possible cause of the fire; ultimately, though, he concluded that the loose connection would, at most, generate an anatomized mist that would be insufficient to cause a fire on its own. Since he could not identify any other possible sources of leaking hydraulic fluid in the evidence available to him at the time of his investigation, he felt that it was more likely the plaintiffs had exaggerated the amount of hydraulic fluid that had been lost from the tractor over the months prior to the incident.
Upon cross-examination at trial, the mechanical engineer took the approach of doubling down on his conclusions in his written report in an attempt to defend them. Given the weak evidence in this case, the mechanical engineer’s defensive demeanor severely undermined his credibility with the Court. In an attempt to convince the Court that the dust cover was the cause of the fire, the mechanical engineer gave evidence at trial that expanded the scope of the conclusions drawn in his written report. Whereas his written report concluded there was only one possible leak of hydraulic fluid at the point of the loose connection, the expert speculated in cross-examination that there may have been additional sources of leaking hydraulic fluid that may have caused the fire. He testified that there could have an additional leak from one of the selective control valves of the tractor, despite having no evidence that he could point to in the physical evidence that remained from the fire.
As his cross-examination continued, the expert continued to attempt to defend his position by further broadening the scope of his initial conclusions in his written report. This strategy lead to him having to deal with contradictory evidence that was being put to him by opposing counsel. First, it was put to the expert that he was not aware the selective control valve had actually been worked on by technicians two days before the fire. Nevertheless, the expert continued to double down by maintaining, without additional evidence, that the selective control valve could had been leaky. Then, it was put to the expert that his testimony at trial differed from his written report. The expert attempted to justify his testimony by stating that he had broadened his opinions upon reviewing expert reports generated after his own. The expert was then forced to admit that there were no such further expert reports that were generated after his own in this case.
In the result, because the mechanical engineer struggled to admit potential weaknesses in his opinion, the Court found issues with the reliability of his evidence, and while the Court did not fully discount his opinion, the Court was unable to fully rely on it.
The second example we look at is the situation where the expert did concede the limitations in his opinions due to the limitations in the evidence available to him during his investigation. Like the mechanical engineer, the metallurgist retained by the manufacturer to assess the welds of the dust cover was also required to form an opinion based upon compromised evidence. By the time this expert was retained, the dust cover was already severely corroded and had been detached entirely from the tractor. The expert metallurgist was not able to view the driveshaft itself and could only assess the portion of the welds on the dust cover. However, from what he was able to review, he was able to arrive at an opinion that the welds on the dust cover could not have been the cause of the fire because he could not identify any intrinsic defects in the welds. As such, he concluded that the dust cover could not have been faulty because the welds likely would not have failed without an external influence.
Rather than becoming defensive when his opinion was challenged, the metallurgist conceded the limitations of his opinions. Specifically, he conceded that the corrosion on the dust cover made it impossible for him to confirm the specific mode of detachment of the dust cover from the tractor. By avoiding becoming defensive and argumentative over the weaker parts of his opinions, the metallurgist was able to shift the focus of his testimony to the stronger points of his analysis, namely, the lack of evidence that the welds were intrinsically defective, which made it less probable that the dust cover was faulty, even if it did become detached by unknown means prior to the fire.
The Court found the metallurgist’s evidence to be helpful and informative. The Court assessed the metallurgist to be a neutral rather than defensive witness. This is important since the role of an expert witness is to assist the Court, rather than to advocate for one side or another. Because the metallurgist made logical concessions based on the weakness of the evidence underlying his opinion, his opinion was largely unchallenged on cross-examination. Ultimately, the Court accepted the metallurgist’s opinion without reservation.
Can the Court make a ruling on the probable cause of a fire when the expert evidence indicates the cause of the fire is undetermined?
When the evidence is particularly compromised, often the experts will ultimately determine that the cause of the fire is undetermined. However, that finding is not the end of the inquiry for the Court into the probable cause of the fire. The Court will consider all other sources of evidence, such as circumstantial or eyewitness evidence, in order to determine whether the Court is able to draw a logical inference as to the probable cause of the fire on a balance of probabilities. Put another way, the plaintiff may be able to prove that something was the probable cause of the fire if there is some reasonable evidence that that something could be the cause of the fire, and all other reasonable possible causes have been eliminated as probable causes. At that point, the Court may infer that the probable cause alleged by the plaintiff was, in fact, the actual cause of the fire – even when the experts agree that the cause of the fire is underdetermined.
In this case, the Court’s inquiry into the evidence of probable cause of the fire ended at the expert opinion evidence because the plaintiffs were asking the court to draw the inference that the allegedly faulty dust cover was the probable cause of the fire without adequately eliminating other possible causes of the fire, such as a potential leak of hydraulic fluid.
Conclusion
This case presents some reminders for plaintiffs, or their insurers, in fire cases with compromised evidence. First and foremost, it is important to be proactive and take immediate steps to preserve any evidence. Evidence preservation was a major issue in this case, but none of the mistakes made with the storage or transport of the evidence amounted to spoliation of the evidence as none of it was intentionally done. The expert evidence in this case would likely have been much more useful and cost-effective had the evidence been properly preserved.
Where litigants are faced with evidence that is severely compromised, as it was in this case, the best course of action is to obtain and provide an expert opinion that acknowledges of the limitations of the evidence and/or the testing that can be done with that limited evidence.