Workplace Incident Investigation: Ontario Requirements and Best Practices
5 min read
When a workplace incident occurs in Ontario, the Occupational Health and Safety Act places specific obligations on employers to investigate, report, and correct. Too many businesses treat incident investigation as a paperwork exercise — filling out a form and moving on. Done correctly, incident investigation is one of the most powerful tools in your health and safety program. It identifies root causes, drives real corrective actions, and demonstrates to workers and regulators that safety is taken seriously. Here is what Ontario law requires and what best practice looks like.
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All critical injuries must be reported to the Ministry of Labour immediately by phone, with a written report to follow within 48 hours
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Near misses must also be investigated — they are free lessons that show where your next serious injury is coming from
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Investigations must be completed by the constructor or employer and a JHSC worker representative as soon as possible after the incident
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Focus on root causes, not blame — ask 'why did the system allow this to happen?' not 'who made a mistake?'
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Corrective actions must be specific, assigned to a responsible person, and have a completion deadline — vague actions get ignored
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Keep all investigation records on file — the Ministry of Labour can request them at any time and will review them following a serious incident
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