Workplace Harassment Investigations in Ontario: What the Law Requires

A complaint lands on your desk. An employee says a coworker has been making their life miserable. Or maybe you heard about it secondhand, and nobody has filed anything in writing. Either way, the clock is already running. A workplace harassment investigation in Ontario is not optional under the Occupational Health and Safety Act(OHSA) — it is a legal obligation that attaches the moment you become aware of an incident or complaint. Get it wrong and you are looking at Ministry of Labour orders, human rights complaints, and civil damages that can reach well into five figures. This post explains exactly what Ontario law requires, where employers most often stumble, and what a defensible process looks like in practice.

What Ontario Law Actually Requires

The OHSA is the primary source of an Ontario employer’s obligation to investigate workplace harassment. The Act requires every employer to maintain a workplace harassment policy and a program that supports it. That program must explain how complaints are made and investigated, how confidentiality will be protected, and how an employee can report harassment when the alleged harasser is the supervisor or the employer itself.

When an incident or complaint comes to the employer’s attention, the OHSA requires an investigation that is appropriate in the circumstances. That phrase matters. It does not demand a forensic audit for every interpersonal dispute, but it does require a process that is proportionate to the seriousness of the allegation. At minimum, the law expects an impartial investigator, interviews of the complainant, the respondent, and relevant witnesses, a review of documentary evidence, and a written outcome notice to both parties describing the results and any corrective action taken or planned.

The program must also be reviewed at least annually. The OHSA covers workplace harassment broadly — not only sexual harassment, but any vexatious comment or conduct against a worker that is known or ought reasonably to be known to be unwelcome. Where the conduct also touches a protected ground under the Human Rights Code— race, disability, sex, and so on — the Ontario Human Rights Commission says employers must act promptly, fairly, and effectively, which in practice almost always means a proper investigation.

The Trigger: When the Investigation Obligation Starts

Ontario employers sometimes assume the duty only kicks in when a formal, written complaint is filed. That assumption is wrong and expensive. The OHSA standard is awareness of an incident or complaint — not receipt of a completed form. Courts have confirmed this. In Metrolinx v. Amalgamated Transit Union, Local 1587, the reasoning reinforced that employers may be required to investigate and address harassment even where the complainant does not pursue a formal complaint.

In practical terms: if a supervisor hears from a team member that someone is being harassed, if HR is told informally, or if management witnesses conduct that could meet the definition of harassment, the investigation obligation has likely been triggered. Waiting for someone to submit a form is not a defense. Document what you knew and when you knew it, then move.

Common Employer Mistakes That Create Liability

Most harassment investigation failures in Ontario come down to the same repeating errors. Knowing what they are is the first step to avoiding them.

Delay. Sitting on a complaint for weeks signals that it was not taken seriously. Courts and the Ministry of Labour both notice slow timelines. Move within days of becoming aware, not weeks.

Using a biased or conflicted investigator. The investigator must be impartial. In Rutledge v. Markhaven Inc., the court took specific issue with the apparent link between the investigator and the employer’s legal counsel. The investigation must not only be independent — it must look independent to the parties involved.

Skipping procedural fairness. Both the complainant and the respondent are entitled to know the substance of the allegations and to have a meaningful opportunity to respond. Investigating one side of the story without giving the other side a real chance to reply is a fast track to a finding of bad faith.

Incomplete evidence gathering. Missing key witnesses, skipping relevant documents, or failing to assess credibility properly undercuts the reliability of any conclusion the investigation reaches. The standard is not perfection, but it is thoroughness appropriate to the circumstances.

Poor confidentiality controls. Sharing more information than necessary exposes the employer to retaliation claims and additional liability. Keep disclosures to what each person legitimately needs to know to participate in the process.

Ignoring trauma-informed approaches in serious cases. In matters involving sexual harassment or alleged violence, insensitive interviewing can distort evidence, cause complainants to withdraw, and create its own harm. The investigator needs to understand how trauma affects memory and disclosure.

What a Defensible Investigation Looks Like Step by Step

A legally defensible workplace harassment investigation in Ontario follows a consistent structure regardless of the size of the organization. Here is what that looks like in practice.

Step 1 — Assess and assign.When the complaint or incident comes to your attention, assess whether interim protective measures are needed while the investigation proceeds — for example, temporarily reassigning schedules so the parties are not working side by side. Then assign an investigator who has no conflict of interest and who has received appropriate training on how to conduct harassment investigations under the OHSA.

Step 2 — Notify the parties. Inform the complainant and respondent in writing that an investigation is being conducted, what the process will look like, and what confidentiality protections apply. Remind both parties of the prohibition on retaliation.

Step 3 — Gather evidence. Interview the complainant first, then the respondent, then witnesses. Review documents, emails, text messages, surveillance footage, and any other relevant records. Take detailed notes. Contemporaneous documentation of who said what, and when, is critical if the investigation is ever challenged.

Step 4 — Assess credibility and make findings. The investigator weighs the evidence, assesses the credibility of the accounts on the balance of probabilities, and reaches conclusions about whether the conduct described constitutes workplace harassment under the OHSA definition.

Step 5 — Report and notify.Prepare a written investigation report. Then provide written notice to both the complainant and the respondent of the results of the investigation and any corrective action taken or planned. This is a statutory requirement, not a best practice. The outcome notice does not have to disclose every detail of the report — but it must communicate the results and what the employer is doing about them.

Consequences of Getting It Wrong

The consequences for a botched workplace harassment investigation in Ontario are real and can be costly. Ministry of Labour inspectors enforce the OHSA requirements directly. They can order an employer to conduct a proper investigation and, where the employer lacks the capacity or objectivity to do so internally, they can order the employer to retain an external investigator — at the employer’s expense.

Where the harassment involved a protected ground under the Human Rights Code, the complainant can file a complaint with the Human Rights Tribunal of Ontario. A finding that the employer failed to investigate or responded inadequately can result in substantial general damages and, in egregious cases, public interest remedies that go well beyond the immediate parties.

In civil wrongful dismissal proceedings, Ontario courts have awarded aggravated or moral damages where the manner of an employer’s response to harassment — including a sham or cursory investigation — caused foreseeable mental distress. The Rutledge v. Markhaven Inc. decision serves as a concrete example, with the court awarding $50,000 in bad faith damages tied in part to the integrity of the investigation process. These awards are not hypothetical. They happen to employers who cut corners.

When to Bring In an External Investigator

Not every harassment complaint requires an external investigator, but some situations make internal investigation genuinely unworkable. You should consider retaining an external neutral when the alleged harasser is a senior leader or HR professional, when the internal investigator has any connection to either party, when the complaint is complex or involves multiple complainants, when prior internal investigations have been challenged, or when the organization is too small to have anyone truly independent available.

An external investigator brings impartiality, specialized training, and a documented process that is much harder to attack on appeal or in litigation. The cost of an external investigation is almost always lower than the cost of defending a damages award that traces back to investigation failures.

When selecting an external investigator, look for someone with demonstrated experience in Ontario workplace investigations, training in procedural fairness and evidence assessment, and no prior relationship with either party or the organization. The investigator should be in a position to give you a final written report that a court or tribunal could scrutinize without embarrassment.

Keeping Your Policy and Program Current

The OHSA does not let employers set a harassment program once and forget about it. Annual review is mandatory. That means checking that the policy still reflects the current workplace structure, that the program identifies how complaints will be investigated and by whom, that alternate reporting routes exist when the supervisor or employer is the subject of the complaint, and that employees have actually been made aware of the program.

A harassment policy that sits in an employee handbook nobody reads is not a defense. Train your managers. Post the policy where workers can see it. Make sure supervisors know what to do the moment a concern is raised, because the first thirty minutes after a complaint surfaces often determine how defensible the rest of the process will be.