Can Lay Witnesses Provide Opinion Evidence?

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Can Ministry of Labour Inspectors or Officers (i.e. lay-people) offer opinion evidence?

Brief Answer:

Yes (probably).


In R. v. Graat, the Supreme Court of Canada, for the first time, permitted an exception to the long-standing rule that lay-witnesses were excluded from providing opinion evidence. In that case, a police officer was able to opine on degree of intoxication.

Following Graat, the circumstances in which lay-witness opinion evidence is admissible have been summarized by David Paciocco and Lee Stuesserin The Law of Evidence, 2nd Ed., (Toronto: Irwin Law Inc., 1999) at p. 127 as follows:

A court may receive lay witness opinion evidence from a lay witness where:

  • (1) they are in a better position than the trier of fact to form the conclusion;
  • (2) the conclusion is one that persons of ordinary experience are able to make;
  • (3) the witness, although not an expert, has the necessary experiential capacity to make the conclusion; and
  • (4) the opinions being expressed are merely a compendious mode of stating facts that are too subtle or complicated to be narrated as effectively without resort to conclusions.[1]

Nevertheless, once satisfied by the evidence in a voir dire that the opinion evidence is admissible, the ultimate weight to be given to the opinion will be up to the trier of fact (i.e. the judge or jury).[2]


(1) Is the inspector in a better position than the trier-of-fact to form the conclusion?

The first prong turns on the added benefit of first-hand observation. For example, in Graat, where non-expert opinion evidence was admitted, the witnesses had an opportunity for contemporaneous, personal observation, and the opinion was based on perceived facts as to the manner of driving and the indicia of intoxication of the driver. These witnesses were therefore in a better position than the trier of fact to determine the degree of impairment and could give the court real help.Therefore, where contemporaneous observation benefits the account of a set of facts, the first element in the above-noted test is probably satisfied.

 (2) Is the inspector’s conclusion one that persons of ordinary experience are able to make?

The second prong asks whether the opinion evidence offered by the inspector requires special knowledge going beyond that of ordinary persons. If so, then the expert opinion rule should be used.[3] For example, persons of ordinary experience may be able to estimate the speed of a car, but not the speed of an airplane. A lay person may therefore offer opinion evidence as to the speed of a car, but only an expert can offer opinion evidence as to the speed of an airplane.

Nevertheless, there is some jurisprudence that suggests lay witnesses may opine on evidence not derived from ordinary experience where special circumstances exist. For instance, the Manitoba Court of Appeal decision in R. v. Ilina allowed two lay witness police officers to opine that a crime scene had been cleaned. There, the court stated that the capacity of the officers to form that opinion “was part and parcel of their professional experience to assess the crime scene.” In Ontario, a similar line of reasoning was established in R. v. Rados, 2009 ONCJ 166 (CanLII). There, the court held that the manager of the department responsible for the installation of traffic signs and placement of pavement markings in Toronto was able to give opinion evidence concerning the use of road signs and how those signs are chosen at a particular location.  In allowing the opinion evidence, among other factors, the court stated that

[the manager’s] “experience, background and knowledge obtained from working and dealing with signs related to traffic and safety issues provides him relevant knowledge of categories of traffic signs and the general purpose behind the erection of particular traffic signs on Toronto streets.  In other words, he has the “experiential capacity” of an ordinary person to give factual and opinion evidence on the procedure and erection of signs on highways in the City of Toronto, and to even offer up an opinion as to the purpose and function of a particular sign erected by the City of Toronto.  Furthermore, Pinkerton’s testimony, as from someone employed in the area related to the erection of signs on Toronto streets in relation to traffic safety and the control of traffic and pedestrian movement on those streets gives Pinkerton the necessary and relevant experience and background to testify on why a certain category of sign is specifically located at a certain location.

Therefore, Ilina and Rados stand for the proposition that lay witnesses may opine on “unordinary” matters if they have acquired, through their professional activates, the requisite experiential capacity to do so. As such, Ilina and Rados are analogous to the instant case because skylights and safe work practices around them are “part and parcel” of the inspector’s professional experience.

(3) Does the inspector have the necessary experiential capacity to make the conclusion; and

If the lay-person giving the opinion evidence possesses the kind of knowledge that is gained from experience over a period of time, then this, the third element is satisfied. Put another way, a witness may give an opinion where the facts upon which the opinion is based are assessed on a subconscious level. For instance, when a person assesses the speed of a moving car, he or she does not consciously calculate how many meters it has travelled in how many seconds. Rather, it is experienced and recalled simply as an estimate of speed, and because it is a matter of ordinary experience such an estimate is sufficiently reliable to put it to the trier of fact directly.

(4) Are the opinions being expressed merely a compendious mode of stating facts that are too subtle or complicated to be narrated as effectively without resort to conclusions;

Where the witness can easily communicate information adequately by describing with particularity what has been observed, the witness should not be permitted to express opinion. However, if the facts are too complicated and it is necessary for the witness to give an opinion so that the he or she can sum up more accurately and adequately the facts he or she is testifying about, then opinion evidence is permissible.


Witnesses, as a general rule, may testify only as to observed facts and it is then up to the trier of fact to draw inferences from those facts. As an exception to the aforementioned rule, a lay witness may be permitted to give an opinion only with respect to matters that do not require special knowledge and in circumstances where it is virtually impossible to separate the facts from the inferences based on those facts. A witness testifying that “a person was drunk” is a common example of an opinion that can be provided by a lay witness.

Dutton Employment Law is a leading Toronto occupational health and safety law firm. Contact one of our occupational health and safety employment lawyers if you have any questions concerning this blog.

[1]R v. Graat [1982] 2 S.C.R. 819.

[2]A voir dire regarding the admissibility of the opinion is necessary: see R. v. Leaney[1989] 2 S.C.R. 393.

[3] The decision of the Manitoba Court of Appeal in R v. Ilina to rely on the lay witness exception to receive the opinion of two police officers that a crime scene had been cleaned u8p is therefore controversial. In explaining that decision, the Court remarked that the capacity of the officers to form this opinion “was part and parcel of their professional experience to assess the crime scene”. With respect, if the capacity to make that observation did depend on professional, the admissibility of the evidence should have been tested using the expert opinion evidence rules, not the Graat exception. This is important because only the expert opinion evidence rules are designed to minimize the risks that are presented where a witness purports to have special skill or training not shared by the trier of fact.

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Jeff is an employment lawyer in Toronto. He is the Principal of the Dutton Employment Law Group at Monkhouse Law. Jeff is a frequent lecturer on employment law and is the author of an employment law textbook and various trade journal articles.