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The Role of Expert Witnesses in Personal Injury Cases

After being hurt in an accident caused by someone else’s fault—whether it’s a car accident, slip and fall, dog bite, or defective product—you are entitled to bring a claim for compensation. To succeed in your claim, you must have evidence to prove that the wrongdoer was negligent and that their negligence caused your injuries. You also need to prove the nature and severity of the injuries you suffered as a result of the accident.

It’s essential to gather strong evidence to support each element of your claim. Experts are frequently called upon to provide written reports and/or oral testimony in court in personal injury cases. Evidence from an expert witness often plays a significant role in proving liability, injuries, and losses, and in some situations, expert evidence can make or break a personal injury claim. In today’s blog post, our Oshawa law firm will provide insight into the important role of expert witnesses.

Understanding the role of witness evidence

Generally speaking, witnesses are only allowed to testify about facts they have observed. For example, an eyewitness to a car accident can provide evidence about what they saw or heard at the scene. These “lay witnesses” are not allowed to testify about their opinions.

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Expert witnesses are an exception to the general rule. An expert witness is a person with specialized knowledge who is allowed to provide their opinion and draw inferences about issues within their area of expertise. The expert’s opinion is put forward to provide insight, explain technicalities, and assist the trier of fact (i.e., the judge or the jury) in deciding the outcome of a case.

An expert’s opinion can also be very helpful in resolving a case outside of court. A strong, clear expert report on liability or the nature and extent of an accident victim’s injuries, for example, can sway insurance adjusters, accident claims lawyers, and the parties to the lawsuit that negotiated settlement is best and there is no need for a trial.

Types of experts in a personal injury case

Both the accident victim (the plaintiff) and the alleged wrongdoer (the defendant) are permitted to retain experts in a personal injury case. The defendant’s goal in gathering this type of evidence is to refute your claims or present an alternative explanation for the accident, the cause of your injuries, etc. Common types of expert witnesses in personal injury lawsuits include medical professionals, accident reconstructionists, engineers, rehabilitation specialists, accountants, economists, and mental health specialists. Depending on the issues, some cases may require several expert witnesses to prove the claim.

How expert evidence is used

Here are some examples of how expert evidence may be used to strengthen a personal injury claim:

  • A medical professional can provide expert opinion on the nature of the injuries sustained, including diagnosis, prognosis, and recommended treatments.

    • The medical professional can be your treating physician, or a specialist in the type of injury you sustained (e.g., an orthopaedic surgeon; a neurologist; a psychiatrist); or

    • The medical professional can be a doctor you are required to see for an independent medical examination. Insurance companies often send personal injury claimants to be examined by a medical expert of their choosing.

  • An engineer or accident reconstructionist can gather and analyze information to help explain how the accident occurred (e.g., analyzing stopping distance, visibility of a pedestrian, or where exactly in an intersection the accident occurred).

  • A manufacturing expert can provide opinion on defective design or manufacture if the personal injury claim arises from a faulty product.

  • A rehabilitation specialist can provide expert evidence on the future medical needs of a plaintiff and the expected costs associated with this future care plan.

  • In a case where injuries are catastrophic or so severe that the plaintiff can’t return to their former employment, an occupational therapist can conduct a vocational assessment to identify the kinds of work the plaintiff will be able to perform and quantify their loss of earning capacity.

  • An economist can calculate the value of the plaintiff’s losses over their lifetime, including loss of income earning potential, loss of benefits, and loss of retirement pension.

In addition to the above, both the plaintiff and the defendant can engage expert witnesses to review and respond to expert reports produced by the opposing party.

Both parties in a personal injury case can retain experts to provide insight on an issue or to give an accident lawyer critical information about facts in dispute. As noted above, that can be very helpful and may promote a negotiated settlement of the case. If out-of-court settlement is not possible and a party chooses to call an expert as a witness at trial, the expert’s ultimate duty is to assist the court in an independent and impartial manner. The expert is only permitted to provide evidence on issues within their area of expertise, in light of their education and training. The expert is to present their unbiased opinion—not to advocate for the party who called them to give evidence.

Reach out to our Oshawa personal injury lawyers

If you or a loved one been injured in an accident, we can help you claim compensation for the suffering. Our Oshawa law firm is experienced in cases involving car accidents, dog bites, defective products, brain injury, and catastrophic impairment.

Our team of Oshawa personal injury lawyers will help you consider your possible legal options and assist you through the steps of bringing a personal injury claim. We will walk you through the entire process, from securing evidence—including expert evidence where necessary—and preparing a strong case to negotiating with the insurers representing the party responsible for the accident.

Kelly Greenway Bruce is a full-service law firm with extensive experience in personal injury matters with offices in Oshawa, Lindsay, Kawartha Lakes, Durham Region, GTA and surrounding areas. Contact us today for a free case evaluation.


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