Does WSIB Cover Stress From a Harassing Supervisor in Ontario?

Can you get WSIB benefits for stress caused by a harassing supervisor in Ontario?

It is possible, but the worker must prove both a proper medical diagnosis and conduct that actually meets the definition of workplace harassment. In a September 2026 decision, the Workplace Safety and Insurance Appeals Tribunal (WSIAT) denied a claim because neither requirement was met.

The case is Decision No. 580/26, 2026 ONWSIAT 1047 (CanLII). An employee of a mail delivery carrier filed a WSIB claim in March 2018 for a mental stress injury, attributing it to about seven months of harassment by her supervisor. WSIB denied the claim, the internal appeal level confirmed that denial, and the worker appealed to the Tribunal.

The Tribunal applied WSIB’s Chronic Mental Stress policy (Policy 15-03-14). It acknowledged that workplace harassment is generally accepted as a substantial workplace stressor that can lead to chronic mental stress. But the policy also has firm limits, and those limits decided the outcome.

What medical diagnosis does WSIB need for a chronic mental stress claim?

The policy requires a diagnosis under the Diagnostic and Statistical Manual of Mental Disorders (DSM) before a chronic mental stress claim can even be adjudicated. The Tribunal said the diagnosis usually must come from a regulated health care professional, such as a physician, nurse practitioner, psychologist or psychiatrist.

Here, the medical evidence was limited. The family doctor’s report described a “situational conflictual relationship with work supervisor causing reactive mood dysregulation” and listed the symptoms as “angry mood; reactive stress.”

The Tribunal found this fell short. The report did not name a DSM diagnosis, and it did not describe enough symptoms to infer that the worker met the criteria for one, including a trauma- or stress-related disorder. As examples, the panel explained that acute stress disorder requires at least nine distinct symptoms, while adjustment disorder requires clinically significant distress out of proportion to the stressor, or significant impairment in social, occupational or other functioning.

The panel also noted that the clinical notes referred to substance use issues. The medical reporting did not adequately deal with those issues, which further undermined the reliability of any diagnosis.

Is discipline or performance management considered workplace harassment?

Generally no: under section 13(5) of the WSIA and the policy, stress caused by an employer’s decisions or actions that form part of the management function is not compensable. The policy’s examples include terminations, demotions, transfers, discipline, changes in working hours and changes in productivity expectations.

The worker’s complaints included repeated calls about her start time, disciplinary notices she felt were issued inconsistently, being asked to count extra flyers, a photo of her delivery truck displayed as an example of what not to do, and denied time off.

The documentary record painted a different picture. Letters in her personnel file addressed performance problems, including improper mail distribution and an incident in which a customer was recorded as signing for a package they had not signed for. Those letters also offered help and described her as a valued team member. The supervisor told WSIB that her conduct contributed to the loss of an important account and that she ranked among the top 25 nationally for customer complaints.

On the inconsistent discipline, the supervisor explained that the collective agreement required notice within 10 days of the conduct, which was not always feasible. The panel accepted that explanation as plausible. Co-workers interviewed by WSIB did not confirm that the worker was singled out, and some evidence conflicted with her account of the truck photo.

The panel concluded that the worker’s anger and mood issues were a response to employment decisions, which fall within the management function, and that the employer’s behaviour was not egregious or abusive. Questions about discipline records and performance letters can also arise when an employer alleges termination for cause.

Does a workplace investigation finding harassment guarantee WSIB benefits?

No, the Tribunal weighs a third-party investigation alongside all the other evidence and can reach a different conclusion. The employer hired an outside investigator to review the worker’s complaints. Based on the limited information the worker supplied, only one complaint was substantiated: the number of calls about her start time, which the investigator found were meant to pressure her to start earlier despite no attendance issues.

The Tribunal disagreed. The supervisor explained that similar staff started around 7:00 a.m., the worker arrived hours later and rarely called ahead, and on at least one occasion he brought in someone else to cover her route because he was unsure she would attend. The panel found his concern reasonable, especially given the performance issues, and said the investigator had failed to appreciate those issues.

The panel also pointed out that the worker submitted only excerpts of the investigation report to WSIB, not the full document.

Does it matter when stress symptoms started compared to the workplace events?

Yes, because the Tribunal must be satisfied that the workplace events significantly contributed to the injury. It applies a significant contribution test, meaning the workplace factor must be of considerable effect or importance, although it does not need to be the only cause.

Even if the start-time calls had been unreasonable, the panel noted they happened in March 2017, while the worker began missing time in September 2017. The medical evidence did not show the calls were the precipitating or a significant factor in her symptoms, and no independent evidence confirmed she had an emotional reaction to them.

The Tribunal noted that section 124(2) of the WSIA resolves an issue in the claimant’s favour when the evidence for and against is approximately equal. Here, however, the panel found on a balance of probabilities that the worker was not subject to workplace harassment.

Questions and records to discuss with a lawyer

• Does the medical report name a specific DSM diagnosis and describe symptoms that match its criteria?
• Which incidents can be corroborated by co-workers, emails, texts or other documents?
• How might the employer characterize its actions, such as discipline, scheduling or performance management?
• Is a complete copy of any workplace investigation report available, rather than excerpts?
• When did symptoms begin relative to the specific events relied on, and is that timeline reflected in the medical records?

Every workplace stress claim turns on its own facts and evidence. If you are dealing with a WSIB mental stress claim or a conflict with a supervisor and want to understand where you stand, our Ontario employment lawyers can review your situation. You can reach UL Lawyers through our contact page to discuss your own circumstances.

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This article is automated commentary on a public court decision and is for general information only — not legal advice. Decisions rely on facts unique to each case. If you are affected by a similar issue, contact a lawyer for advice specific to your situation.