Most Ontario employers understand that workplace harassment is serious. What many don’t realize is how specific — and how unforgiving — their legal obligations are when an incident occurs.

Under the Occupational Health and Safety Act, the duty to investigate isn’t triggered only when an employee formally complains. It applies when you become aware of an incident through any means: a third-party report, a manager’s observation, an anonymous tip, or even an off-site event with a clear workplace connection. If you know, you’re obligated to act.

This guide explains what that obligation actually requires, how to conduct an investigation that meets the legal standard, and when to bring in outside expertise.

What Workplace Harassment Means Under Ontario Law

Under Section 1 of the OHSA, workplace harassment is defined as “engaging in a course of vexatious comment or conduct against a worker in a workplace that is known or ought reasonably to be known to be unwelcome.”

The Act also separately defines workplace sexual harassment, which includes unwelcome sexual advances, requests for sexual favors, and conduct of a sexual nature that creates a hostile work environment based on sex, sexual orientation, gender identity, or gender expression.

A few important nuances:

• Course of conduct: Harassment typically involves repeated behavior, not a single incident. However, a single severe incident — particularly involving sexual harassment or threats — can qualify.
• Reasonable management is not harassment. Performance feedback, improvement plans, work assignments, and disciplinary processes — when conducted reasonably and in good faith — do not constitute harassment, even if the employee finds them unwelcome.
• Off-site and off-hours conduct can still be covered if there is a connection to the workplace relationship. Ontario courts have confirmed this applies to incidents after working hours and away from the physical workplace.

When the Duty to Investigate Is Triggered

Section 32.0.7 of the OHSA places an absolute obligation on employers to ensure an investigation “appropriate in the circumstances” is conducted into incidents and complaints of workplace harassment.

Critically, this duty applies:

• When a worker formally files a complaint
• When a worker informally discloses an incident without wanting to file a complaint
• When a manager or supervisor observes conduct that appears to be harassment
• When an incident is reported anonymously or by a third party
• Even when the affected worker explicitly states they do not want an investigation

The last point surprises many employers. You cannot honor a worker’s preference not to investigate if you have knowledge of a harassment incident. Your obligation runs not just to the individual but to the safety of the workplace as a whole.

The Investigation Process: Eight Steps

There is no single prescribed method, but OHSA requires the investigation be “appropriate in the circumstances” — meaning the scope, formality, and thoroughness should match the severity of the allegations.

Step 1: Establish confidentiality and protect parties

Before beginning, limit information about the investigation to those who need to know. Employees involved should be instructed to keep matters confidential, and care should be taken not to inadvertently identify parties through the scope of interviews or communications.

Step 2: Interview the complainant

Start with the person who experienced the harassment. Conduct the interview in a private setting, take detailed notes, and document specific incidents: dates, times, locations, what was said or done, the presence of any witnesses. Avoid leading questions — let the person tell their account in their own words.

Step 3: Notify and interview the respondent

Provide the alleged harasser with a written summary of the allegations and give them a fair opportunity to respond. This procedural fairness requirement is non-negotiable — failing to provide the respondent a genuine opportunity to respond can invalidate your entire investigation.

Step 4: Identify and interview witnesses

Interview anyone who may have relevant direct knowledge. Witnesses should be interviewed separately and asked only what they personally observed — not for their opinions about the parties or the situation.

Step 5: Collect and review documentation

Gather relevant written records: emails, text messages, performance records, security footage if applicable, and any prior complaints or disciplinary records involving either party. Digital communications are often the most important evidence in workplace harassment investigations.

Step 6: Document everything

Maintain detailed notes from every interview and document your decision-making process. If you decide not to take certain steps (e.g., determining that a particular witness has no relevant knowledge), record that reasoning. Your documentation is your defense if the investigation is ever challenged at a tribunal or in court.

Step 7: Prepare findings

Based on the evidence gathered, reach findings of fact. The standard is not “beyond a reasonable doubt” (criminal law) but rather “balance of probabilities” — what is more likely than not to have occurred. Your findings should address each allegation specifically, not in generalities.

Step 8: Communicate results and take corrective action

Both the complainant and the respondent must receive written notification of the investigation results and any corrective action that has been or will be taken. You do not need to disclose specific disciplinary measures, but both parties must receive written confirmation that the process is complete and what, if anything, was done.

Who Can Conduct the Investigation

OHSA does not require a licensed investigator or a lawyer. The investigator may be internal or external, provided they meet the key criteria: they were not involved in the incident and they do not report to or work closely with the alleged harasser.

The Ministry of Labour can order an employer to retain an independent investigator at the employer’s expense if it determines the employer is not equipped to conduct an adequate investigation. This most commonly occurs when the alleged harasser is a senior leader or when the investigation is perceived as biased.

Timeline: The 90-Day Standard

Ontario’s OHSA doesn’t set a hard statutory deadline, but the Code of Practice to Address Workplace Harassment and Ministry guidance specify that investigations should be completed “as soon as possible within 90 days or less.”

Delays beyond 90 days require clear documented justification: witness unavailability, illness, or genuine complexity. Unexplained delays expose the employer to Ministry criticism and support tribunal arguments that the investigation was inadequate or not taken seriously.

In practice, most straightforward investigations should be completed in 30–45 days. More complex multi-party situations may take longer, but active progress should be demonstrable throughout the process.

Confidentiality Requirements

Confidentiality is mandatory — but it’s not absolute. Information about the investigation must be disclosed:

• To the extent necessary to complete the investigation
• To protect workers who may be at ongoing risk
• To enable corrective action
• As required by law — for example, in response to a Ministry inspector’s order

Outside of those exceptions, disclosure should be limited. This means not telling coworkers who is under investigation, ensuring parties do not discuss the investigation with each other while it’s ongoing, and protecting witness identities wherever possible.

Common Mistakes Ontario Employers Make

• Treating an informal disclosure as not requiring investigation. If a worker mentions harassment to a manager but doesn’t want to “make it formal,” your obligation isn’t discharged.
• Having the respondent’s manager conduct the investigation. This creates an obvious conflict of interest and will be challenged.
• Not providing the respondent an opportunity to respond. Procedural fairness requires this even when evidence seems clear-cut.
• Delayed investigations. Starting an investigation months after the incident undermines the integrity of the process and signals to employees that complaints are not taken seriously.
• Incomplete documentation. If you can’t demonstrate what steps were taken and why, the investigation will be difficult to defend.
• Communicating results verbally rather than in writing. Both parties must receive written notification — verbal communication does not satisfy the OHSA requirement.
• Conflating harassment with interpersonal conflict. Not all workplace tension is harassment. Investigations should be proportionate to the nature of the allegations.

Reprisal Protection

Section 50 of the OHSA prohibits reprisals against workers who participate in workplace harassment investigations — including complainants, witnesses, advisors, and investigators. Reprisals include termination, discipline, demotion, intimidation, or any other adverse treatment connected to the worker’s involvement in the process.

This protection applies even when the investigation concludes that the harassment allegation was not substantiated. A complainant who made a good-faith complaint is still protected from negative consequences. Violating this provision is a serious legal risk on top of the underlying investigation obligation.

When to Bring in External HR Support

Most small and mid-size Ontario employers don’t have a trained workplace investigator on staff. Retaining an external HR consultant to conduct a workplace harassment investigation is often the right call when:

• The alleged harasser is a founder, CEO, or other senior leader
• The company is too small to identify a neutral internal investigator
• The allegations are serious — sexual harassment, threats, or physical conduct
• There is a history of prior complaints involving the same individual
• The complainant has indicated an intention to file a Ministry complaint or human rights application
• The company has previously had an investigation challenged or criticized

An external investigator brings documented independence, which protects the employer if the process is later challenged — and which signals to all parties that the matter was handled with appropriate seriousness.

For more on how HR consulting supports employment law compliance obligations in Ontario, see our overview of HR consulting services. If you’re facing an active investigation situation, connect with an HR advisor before proceeding.