Post-Incident Drug Testing Policies in the Age of Cannabis

September 2018

Article by: Mike Hamata

What do low speed collisions, marijuana, and post-incident drug testing have in common? Those are the facts that were before the Alberta Court of Queen’s Bench in Canadian Energy Workers’ Association v ATCO Electric Ltd, 2018 ABQB 258.

In that case, the Court upheld an arbitrator’s award which had found that ATCO’s decision to drug test two employees following a low speed collision at a remote worksite was reasonable.

The decision is interesting in its treatment of post-incident drug testing. ATCO Electric stands for the proposition that requiring an employee to submit to drug testing after an incident continues to be justified where:

(a) the incident is significant, or is a near miss that could have been significant;
(b) the employer asks the employee for an explanation before requiring a drug test; and
(c) there is some basis for the employer to need to rule out impairment as a cause of the incident (the “Weyerhaeuser Criteria”).


In the ATCO Electric case, the first grievor was backing up a very large machine called a Nodwell, when he struck a truck being operated by the second grievor. The collision happened at low speed, and caused about $1,000 in damage. Neither grievor was hurt. After the incident was reported, ATCO decided to drug test both grievors, one of whom tested positive for marijuana. That grievor participated in a drug treatment program and upon completion was returned to work. The Union grieved the drug test requirement.

By the time the issue came before the Court, neither party seriously disputed that (a) the incident could have been significant, or (b) the employer had asked the employee for an explanation. ATCO’s policy was also no longer in dispute. Instead, the Court focused on the third Weyerhaeuser Criteria, i.e. whether there was a sufficient link between the incident and potential impairment to justify requiring a drug test.

Before the Court of Queen’s Bench, both ATCO and the Union attacked the original arbitration panel’s finding for the third Weyerhaeuser Criteria: that testing was justified because ATCO had determined that the incident was caused by “poor judgement”, but also because the grievors had recently received relevant safety training which they did not follow, and because the Nodwell had recently been involved in a similar safety incident.

Importantly, the Court rejected the Union’s argument that ATCO needed evidence that the employee was impaired before conducting a post-incident drug test. Post-incident drug testing and reasonable cause drug testing remain distinct concepts.

The Court also rejected ATCO’s argument that poor judgment alone always justifies post-incident drug testing – something more is required (in this case, the recent training and recent Nodwell accident were that “something more”).

Lessons for Employers

As the Court noted, the “…balancing of an employer’s interest in safety with employees’ privacy rights in their bodily integrity is a nuanced and very fact specific exercise.” The case highlights the following key takeaways for employers:

  1. The law that applies to drug and alcohol testing has evolved significantly over the last five years, and it continues to evolve. Review your drug and alcohol policies and ensure that your policies reflect those changes.
  2. Not every “incident” justifies a post-incident drug test. Employers should be familiar with the law, their own policies, and the relevant circumstances before making a reasoned decision to test an employee for impairment after a workplace incident.