Expert Basics

Last Reviewed: March 2023 Reviewed by: JES Download

Expert Witnesses Basics

An expert is someone qualified with special knowledge, skill, training, and experience, like an engineer or a doctor. An expert can express an opinion based on information that they have personally observed, or information that was provided by others. 

For example, an expert in motor vehicle accident analysis could examine evidence showing the skid marks, and give the court an expert opinion about the speed of the cars involved in the accident.

An expert’s job is to assist the Court. Experts are not to be advocates for either side. This is explained in Part 11 of the Rules of Court, which deals with the evidence of experts. An expert’s duty is to assist the court and not to be an advocate for any party.

Read the Rules

Part 11 Experts

An expert can help the Court draw conclusions from the facts. For example, with the skid mark expert above, the Court may be able to see the skid marks. However, the Court does not know how to conclude from the skid mark how fast the cars were going.

When Do I Need an Expert Witness?

It can be expensive to hire expert witnesses. However, sometimes it is necessary to hire an expert in order to prove part of your case. If your case turns on proving that a car was speeding, simply pointing to skid marks with no expert will probably not prove the point.

An expert is necessary when you need the Court to draw a conclusion that requires knowledge or expertise outside the knowledge and experience of an ordinary person.

You may need an expert to prove (or disprove) liability and damages. 

  • Proving “liability” means proving that the other side was at fault. In an accident , a skid mark expert could help prove liability. Or, if you are the defendant, you may need a skid mark expert to explain why the evidence suggests you were not speeding
  • Proving “damages” means proving (or disproving) that a loss occurred. For example, you may need a doctor to explain your injuries and how they are expected to affect your life going forward

As it can be expensive to hire an expert, and it can cost you to not hire an expert if one is needed, getting legal advice on what, if any, expert evidence you need is a good idea. For help finding a lawyer, see Get Help.

Who Can Act as an Expert Witness?

In order to act as an expert, the Court must accept that the witness has acquired special knowledge through study or experience on the subject at issue. Further, the individual must be unbiased (and appear unbiased). The expert cannot appear to favour one side or the other.

When considering if someone can act as an expert witness, the Court may ask:

  • Have they given expert evidence before?
  • Do they have any degree or certificate?
  • Do they have professional qualifications?
  • Are they members of professional associations related to the proposed evidence?
  • Have they attended additional courses and seminars on the subject?
  • Have they taught about the subject?
  • Have they kept up with changes in the field?
  • How long have they been involved with the subject at issue?
  • How long have they worked in the field at issue?

It is not necessary for an expert to satisfy everything listed above. However, the judge must be satisfied that the witness has acquired enough special knowledge to help the Court.

Where to Find Expert Witnesses?

Finding an appropriate expert can take a while. When you think you may need expert evidence, it is a good idea to start your search right away. Do not reach out to just one individual. You will instead want to speak to a number of people to see who will be a good fit..

A good place to start is with an online search. You may also want to review the website of a professional organization in the field to see if it has a directory. Try to speak to as many people in the field as possible to get recommendations. You may also speak to people in related fields (for example, if you need evidence from a spinal surgeon, you might get recommendations from a chiropractor). Lawyers also may know experts.

Single Joint Expert

You and the other party can appoint a single joint expert (Rule 11-3).

You must settle certain issues before doing so (for example, the expert you agree to appoint; the issue the expert is being asked to resolve; the agreed facts or assumptions the expert is relying on to reach their opinion).

Read the Rules

Rule 11-3 Appointment of joint experts

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