The Alberta Court of Appeal has provided clarity on what the Crown must prove in a prosecution under the general duty section (previously Section 2(1), now Section 3(1)(a)) of the Alberta Occupational Health and Safety Act regarding the failure to ensure the health and safety of a worker.(1)


The employer had originally been found guilty on two charges, including the general duty offence, following a workplace fatality. The employer successfully appealed the convictions and the summary conviction appeal judge ordered a new trial. The Crown was granted leave to appeal the decision before the Alberta Court of Appeal.(2)


The key question before the Alberta Court of Appeal was whether the expression "as far as is reasonably practicable for the employer to do so" in the general duty section was part of the actus reus; in other words, whether it was part of the physical components of the offence that the Crown had to prove. The majority set out to provide an interpretation of the general duty section that would result in a more comprehensive framework for the actus reus requirement for the general offence provision.

The Crown argued that it could rely on the 'accident as prima facie proof of breach' concept when proving the actus reus in order to satisfy its legal burden. In the majority decision, the court disagreed and determined that the expression "as far as it is reasonably practicable for the employer to do so" formed one element of the actus reus. Therefore, for an offence to occur under the general duty of the Alberta Occupational Health and Safety Act, the Crown must establish the following beyond a reasonable doubt:

  • The worker was engaged in the work of the employer.
  • The worker's health or safety was threatened or compromised (ie, an unsafe condition).
  • It was reasonably practicable for the employer to address the unsafe condition through efforts that it failed to undertake.

The majority found that these elements were consistent with:

  • the language, purpose and intent of the Alberta Occupational Health and Safety Act;
  • the Supreme Court of Canada's guidance in Sault Ste Marie; and
  • the interpretation given to similar provisions in other jurisdictions.

This did not constitute a codification of the due diligence defence and did not undermine the Alberta Occupational Health and Safety Act's basic goals. The majority acknowledged that the employer's obligation to establish due diligence on the balance of probabilities would overlap with the Crown's obligation to prove that it was reasonably practicable for the employer to address the unsafe condition. However, these remained distinct inquiries, which were subject to different standards of proof. In addition, certain factors (eg, mistake and employee error) could affect the due diligence defence in ways that would not affect the actus reus assessment.

The second ground of appeal was whether the appeal judge had erred in her interpretation and application of the due diligence defence. The majority reviewed this issue and determined that the Crown had identified no error in the appeal judge's review of the application of the due diligence defence; therefore, this ground of appeal was dismissed.

In the minority decision (concurring in the result), the justice disagreed that the words "as far as it is reasonably practicable for the employer to do so" constituted part of the physical components that the Crown must prove. The minority decision stated that imposing this requirement on the Crown would require it to prove:

  • standard industry practices;
  • what a reasonable company would have done; or
  • that the measures taken by the employer were insufficient and unreasonable.

Thus, the Crown would have to prove negligence or negate due diligence. However, it would not always be possible for the Crown to prove exactly how a workplace incident occurred, which is why the general duty was set out in the Alberta Occupational Health and Safety Act. Therefore, to establish the physical components for the general duty offence, the minority held that the Crown need only prove beyond a reasonable doubt that something happened within the control of an employer that negatively affected the health or safety of its workers.

The minority agreed that the appeal should be dismissed and the matter sent back for a new trial.(3)

For further information on this topic please contact Cristina Wendel at Dentons by telephone (+1 780 423 7100) or email ( The Dentons website can be accessed at


(1) R v Precision Diversified Oilfield Services Corp, 2018 ABCA 273 (CanLII).

(2) For more information on the background and history of the proceedings please see "Is compliance with industry standards enough to establish due diligence? Alberta Court of Appeal set to consider this issue".

(3) For more information please see

This article was first published by the International Law Office, a premium online legal update service for major companies and law firms worldwide. Register for a free subscription.