Expert Evidence – Doctors, Biomechanical Engineers and Force Necessary to Cause Injury
When a personal injury claim is advanced the Plaintiff has the burden to prove what injuries they suffered and that these were caused (or materially contributed to) by the trauma in question. In proving a case it is common for a Plaintiff to obtain expert opinion evidence from medical doctors to address issues such as diagnosis of injury, prognosis, treatment needs, disability and causation.
One tactic used by personal injury lawyers is to try and limit the scope of the opposing sides expert witness’ opinions. If a witness wanders outside of their area of expertise then those portions of their opinion become inadmissible.
When addressing the issue of causation a developing area of BC Injury Law is whether a physician can give opinion evidence with respect to the forces necessary to cause a specific injury. Some argue that this is outside of a medical doctors training and is better left to biomechanical engineers. Reasons for judgement were released today by the BC Supreme Court, Vancouver Registry, dealing with such an argument.
In today’s case (Pham-Fraser v. Smith) the Plaintiff sustained numerous injuries in a 2006 BC car crash. The Plaintiff’s vehicle was struck at an intersection when the Defendant entered against a red light. The issue of fault was admitted focusing the trial on the issue of damages.
In support of her case the Plaintiff called numerous physicians to give expert opinion evidence. One of these witnesses was Dr. Brian Hunt, a neurological surgeon. He provided the opinion that the “accident created sufficient deceleration forces to produce damage to (the plaintiff’s) L5 vertebra through abnormal axial-loading but that a biomechanical engineer (would need to) confirm this probability“.
The Defence lawyer argued that Dr. Hunt was simply not qualified to give this opinion and that this opinion was inadmissible. Mr. Justice Greyell rejected this submission and provided the following useful analysis:
 Mr. Killas argued certain aspects of the expert evidence called by the plaintiff were inadmissible and that other expert opinion evidence should be given little or no weight. In particular the defendants argued I should give little or no weight to Dr. Hunt’s opinion the accident created sufficient forces to produce damage to the L5 vertebral body through abnormal axial loading. Mr. Killas pointed out Dr. Hunt then qualified this opinion with this remark: “However a biomechanical engineer will need to confirm this probability”. Mr. Killas noted Dr. Hunt had not done an investigation into the circumstances of the accident (vehicle speed, etc.) to make his opinion.
 Mr. Killas also argued Dr. Hunt’s diagnosis that the plaintiff sustained a brain dysfunction secondary to brain injury was simply based on the reading of Dr. Longridge’s medical report and on an unproven assumption the plaintiff had a lack of awareness of the circumstances of the motor vehicle accident. Mr. Killas also argued Dr. Hunt’s opinion the plaintiff probably suffered abnormal axial loading on her spinal column during the accident was qualified by Dr. Hunt when he said in his report that “a biomechanical engineer will need to confirm this probability”.
 I accept Dr. Hunt’s opinion on both these issues. There was evidence concerning the plaintiff’s limited recollection of what happened following the accident and I accept Dr. Hunt, given his qualifications and special experience, was well able to offer the opinions he did.
 I have ascribed as much weight to Dr. Hunt’s opinion concerning the cause of the plaintiff’s lower back injury as I have on the opinions of the other specialists who testified, including Dr. Schweigel. Dr. Hunt’s expertise (and that of the others) has been gained through many years treating patients who have been involved in motor vehicle accidents. He is well qualified to offer the opinion he did. The fact Dr. Hunt was prepared to defer to the opinion of a biomechanical engineer does not, in my view detract from his expertise in offering his opinion to the court on the cause of the plaintiff’s lumbar spine injury. I similarly find that the evidence of Dr. Hartzell concerning the forces applied to the plaintiff’s lower spine during the accident is helpful to the court and hence admissible, given his experience and qualifications. Both Dr. Hunt and Dr. Hartzell, through their long and distinguished medical practices have had experience with persons with spinal injuries.