Although we traditionally think of “due diligence” as proving that an employer took all reasonable steps to protect its workers and/or prevent an accident from occurring, there are actually two separate forms of the defence. Although they are very closely related, the second (and less discussed) form of due diligence is slightly different, in that it provides a defence where an employer “reasonably believed in a mistaken set of facts which, if true, would render the act or omission innocent”.

The difference between the two forms, and the importance of forseeability and the actions taken (or not taken) by the employer in both, is illustrated in the following cases:

  • In R. v. Value Drug Mart Associates Ltd., a worker was injured while bending down under a conveyor to plug in a portable weigh scale. An investigation determined that her hair had become entangled in an unguarded drive shaft that was under the conveyor.

Raising the defence of "mistake of fact", company officials all testified that they believed guarding was in place. However, the Court found that the facts simply didn’t support the company’s claims, especially in regards to whether their beliefs were reasonable. In particular,  the Court pointed out that the “mistaken belief” of the company officials continued for a period in excess of four years - during which time, the Court suggested, someone surely would have walked past and noticed (or should reasonably have noticed) the lack of guarding. As a result, the defence failed, and the company was found guilty.

Employees of the company had been told by a contracting firm that the ground "was clear". The employees took that to mean that the exact location of utilities had been located and marked. As such, having walked around the site and not observed any markers that would indicate underground services, they began to excavate. After only a short time, however, they struck concrete. Upon being advised of the strike, the contracting firm informed the employees that the concrete was part of an old nursing station, and that they should continue digging. The backhoe operator continued to dig, struck a hydro duct, and was electrocuted.

The company argued “mistake of fact”, but both the trial and appeal courts found that it was not objectively reasonable for the company to have accepted and acted upon the contracting firm’s statement without further inquiry. While the Court of Appeal acknowledged that a party is, in certain circumstances, able to rely on the advice of a third party for its mistaken belief, it also made clear that one of the key factors to be considered in assessing the reasonableness of that reliance, is the gravity of the potential harm should that advice prove to be wrong. 

  • In R. v. Rio Algom Ltd., a damaged gate swung into the path of a mining car, fatally crushing an employee. The damage to the gate and overswing were both known by the company, although the extent of the resulting danger seemingly was not.

In finding the company guilty, the Court made it clear that the “mistake of fact” defence cannot prevail where an accused simply proves that it was mistaken in believing there was no danger of injury to an employee, as a result of its own failure to ensure that equipment or protective devices were maintained in good condition or that every precaution reasonable in the circumstances was taken for the protection of a worker.

In other words, the Court was saying that for the defence to work, there must be a reasonable but mistaken belief in some underlying set of facts, as opposed to the resulting and/or accompanying danger. Knowing the facts, but failing to consider the potential danger that may result from those facts, will not render an act or omission innocent.

Understanding the case law in this area is important for a couple of reasons. First, it gives us some insight into how the courts approach these types of cases and these particular types of issues, and what we need to establish in order to be successful. And second, courts operate on a principle known as “stare decisis”, which essentially means that similar cases with similar issues ought to be treated in a similar fashion. So much so, in fact, that if the facts and issue in one case are decided a certain way in a higher level court within the same province, a lower level court is compelled to find in the same way. Of course, the facts of any two cases are always going to be different, but a part of our goal is to identify which cases we think are most relevant and appropriate (and helpful!), and to then argue that the judge hearing our case should follow the same rationale as in that earlier decision.