Am I Legally Required to Investigate? Ontario Guide

It's 11pm. You've just received an email from an employee describing harassment. Your immediate question isn't "how do I fix this?" — it's "am I legally required to investigate?"

The answer is yes. And the consequences of skipping it are severe enough that you need to take this seriously.

The Legal Framework (Yes, It's Real)

Ontario doesn't have a single "investigation statute." Instead, your obligation to investigate comes from three overlapping legal sources:

1. Occupational Health and Safety Act (OHSA) OHSA section 32.0.7 requires an employer to ensure that an investigation "appropriate in the circumstances" is conducted into incidents and complaints of workplace harassment. When you receive a harassment complaint, an investigation is required. This applies to provincially regulated workplaces in Ontario. See OHSA Section 32: Employer Investigation Obligations for detailed compliance requirements.

2. Ontario Human Rights Code The Code makes employers responsible for a workplace free of discrimination and harassment based on protected grounds. When a complaint reaches the Human Rights Tribunal of Ontario (HRTO), decisions have examined how the employer responded — including whether it investigated reasonably — in assessing liability and remedies.

3. Just-cause termination principles If you terminate for cause based on unverified allegations, a court hearing a wrongful dismissal claim will examine whether you conducted a fair investigation and had a reasonable basis for the decision. An inadequate process undermines a cause defence.

These aren't optional frameworks. Note that federally regulated employers operate under a different framework — see Bill C-65 Investigation Requirements for Employers if your organization falls under federal jurisdiction.

For a detailed breakdown of OHSA Section 32 requirements and enforcement, see OHSA Section 32: Employer Investigation Obligations.

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Considering external support for an Ontario employer-side matter? Review our workplace investigation fit and acceptance process. It explains the screening and delivery boundaries; it does not determine which legal framework applies to a specific matter.

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What "Legally Required" Actually Means

A legal obligation to investigate means:

• You must respond to the complaint in writing — acknowledge receipt and provide a timeline
• You must conduct a reasonably thorough investigation — not a cursory chat with the person involved
• You must interview relevant witnesses — people with direct knowledge
• You must document the investigation — notes, interview summaries, evidence
• You must reach findings based on evidence — "on the balance of probabilities" in Canadian law
• You must communicate outcomes (with appropriate confidentiality constraints)
• You must take remedial action if misconduct is found

If you skip investigation and fire the person instead, you're exposed to:

• A wrongful dismissal claim, with severance exposure driven by tenure, age, and role
• An HRTO application, where remedies can include lost wages and damages for injury to dignity
• A WSIB/occupational health claim if stress/mental health injury is involved
• A constructive dismissal claim if the complainant leaves instead

When Investigation Is Absolutely Mandatory

1. Any Harassment or Violence Allegation Under OHSA, workplace harassment (a course of vexatious comment or conduct against a worker that is known, or ought reasonably to be known, to be unwelcome — no connection to a protected ground is required) triggers mandatory investigation. This includes sexual harassment, harassment tied to a protected ground, or any pattern of unwelcome conduct. Importantly, under the Metrolinx ruling, you must investigate incidents of harassment even without a formal complaint.

2. Discrimination Claims If someone alleges they've been treated differently because of race, gender, age, disability, religion, sexual orientation, family status, marital status, gender identity, or gender expression — investigate. The Human Rights Code makes this non-negotiable.

3. Safety Concerns Someone reports unsafe working conditions, equipment failure, or health/safety violations — investigate. OHSA requires it.

4. Serious Misconduct with Liability Allegations of theft, fraud, breach of confidentiality, conflict of interest, or gross insubordination that could result in termination — investigate. Otherwise, your termination decision rests on unverified allegations and is unlikely to survive scrutiny.

5. Complaints That Involve Multiple People One-on-one conflict often settles privately. But when multiple people report the same issue ("I've heard he's treated three female employees this way") — that's a pattern, and pattern requires investigation.

What Happens If You Don't Investigate

Scenario 1: You Don't Investigate, But Keep the Person Result: The complaint is on record. The harassment continues (or appears to). The complainant files an HRTO application naming you as the employer, and your failure to investigate becomes part of the case against you. Remedies at the HRTO can include lost wages and damages for injury to dignity, feelings, and self-respect.

Scenario 2: You Don't Investigate, You Terminate the Complainant Result: A wrongful dismissal claim plus a human rights complaint alleging reprisal. You've terminated without cause and without due process, and the reprisal allegation compounds the exposure.

Scenario 3: You Don't Investigate, You Terminate the Respondent Result: The respondent sues for wrongful dismissal — they never got an opportunity to respond, and the termination rests on unverified allegations. A failed cause defence typically means paying full common law notice, plus legal costs on both sides.

Scenario 4: You "Investigate" Improperly (Bias, Conflict of Interest, No Due Process) Result: The investigation is challenged as unfair. If a tribunal finds the investigation itself was discriminatory or procedurally flawed, your investigation doesn't protect you — it becomes part of the claim.

Outcomes vary widely with the facts, but the cost of not investigating, or investigating poorly, routinely dwarfs the cost of doing it properly. Investigation fees are quoted after intake — you receive a written fee and scope before work begins.

What "Reasonable" Investigation Looks Like Under Ontario Law

Case law from the HRTO and courts has established what a fair, thorough investigation looks like:

• Timeliness — Start promptly and tell the parties the expected timeline. Unexplained delay suggests you didn't take the complaint seriously.
• Independence — Investigator has no conflict of interest with either party.
• Due process — Both complainant and respondent are interviewed. Respondent gets opportunity to respond to allegations.
• Evidence-based — Credibility is assessed systematically. You can't just believe one person over another because you like them better.
• Documentation — Interview summaries, timeline of events, evidence list, reasoning for credibility findings.
• Clear findings — You state what happened, or didn't happen, and why you concluded that.
• Appropriate remediation — If misconduct found, reasonable corrective action is taken.

Missing even one of these elements weakens your defense in a tribunal hearing.

For a complete walkthrough of the investigation process and what to expect at each stage, see The Complete Guide to Workplace Investigations in Ontario.

The Common Mistakes That Destroy Your Legal Position

Mistake 1: Manager Investigates a Complaint Against Their Own Employee The manager has a conflict of interest. Whatever they find will be questioned. Use an external investigator or HR professional instead.

Mistake 2: You Investigate, Find Misconduct, Do Nothing You've documented the problem — now you're liable for ongoing harm. Finding misconduct requires action (counseling, suspension, termination, retraining). Inaction is negligence.

Mistake 3: You "Investigate" via Email Written email can't assess credibility, tone, body language, or clarify contradictions. Interviews must be in-person or video (at minimum). Email-only investigation looks negligent in tribunal proceedings.

Mistake 4: You Don't Preserve Evidence As soon as a complaint arrives, preserve the relevant communications — emails, Slack messages, calendar invites, video calls. Evidence that disappears after a complaint undermines the investigation and your credibility. Whether formal litigation-hold obligations apply in your situation is a question for your counsel — confirm before relying on informal practice.

Mistake 5: You Tell the Complainant "Don't Talk to Anyone" Reasonable confidentiality ≠ gag order. Complainants have the right to discuss their complaint with a union rep, lawyer, or trusted colleague. Over-restricting their speech looks retaliatory.

Your Actual Legal Obligation in Plain Language

When you receive a complaint of harassment, discrimination, or serious misconduct:

1. Acknowledge it in writing, promptly
2. Choose an appropriate investigator — internal where a trained, conflict-free person exists; external (HR professional or lawyer) where complexity, seniority, or legal risk calls for it
3. Conduct interviews with both parties and relevant witnesses
4. Document findings based on evidence
5. Communicate outcomes to the complainant and respondent (maintaining appropriate confidentiality)
6. Take remedial action proportional to the findings
7. Follow up to ensure no retaliation and that remediation worked

The duty to investigate is statutory. The steps above are the practice that decisions from tribunals and courts consistently look for when they assess whether an employer met it.

When You're Unsure About Your Obligation

Ask yourself these questions:

• Is there an allegation of unwelcome conduct? (OHSA applies)
• Does the allegation involve a protected ground (gender, race, age, disability, etc.)? (Human Rights Code applies)
• Could this person be fired for what's alleged? (Due process required)
• Would a reasonable employer investigate this? (Common law applies)

If you answer "yes" to any of these, you need an investigation.

For guidance on executing each step and understanding the investigation timeline and process, see Workplace Investigation Process: Step-by-Step Guide.

The Bottom Line

You are legally required to investigate complaints of harassment, discrimination, and serious misconduct in Ontario. The law comes from the OHSA, the Human Rights Code, and common law principles established through decades of tribunal and court decisions.

The cost of not investigating — settlements, awards, legal fees, reputational damage, and operational disruption — routinely exceeds the cost of investigating properly. Investigation fees are quoted after intake, based on the number of parties, evidence volume, urgency, jurisdiction, and reporting scope; you receive a written fee and scope before work begins.

Not sure whether your specific situation requires an investigation? Talk to us. We'll walk you through the framework that applies, outline what an investigation would look like, and help you make the right decision. This article is general information, not legal advice — for advice on a specific situation, consult employment counsel.