Can my boss force me to take a drug test?

Short answer: Sometimes, but only in narrow circumstances. In Ontario, workplace drug and alcohol testing sits at the intersection of human rights, privacy, and safety law. Random or blanket testing is rarely justified. Testing usually needs a compelling safety reason, careful limits, and meaningful accommodations for disability (including addiction).

The legal balancing act (in plain English)

Ontario law tries to keep two truths in view at the same time:

• Safety matters. Employers have legal duties to keep workplaces safe, especially in safety-sensitive roles (think heavy machinery, transit, energy, nursing, certain construction tasks).

• Dignity and privacy matter. Addiction is a disability under the Human Rights Code. Testing can be intrusive, and results are sensitive medical information.

Courts and tribunals weigh these interests. The upshot: an employer must show that the need for testing outweighs the intrusion on privacy in the specific workplace and that the approach is as minimally intrusive as reasonably possible.

When testing is generally allowed

1) Reasonable cause or post-incident

If there’s objective reason to suspect impairment (e.g., slurred speech, erratic behaviour, odour of alcohol/drugs, or a significant accident/“near miss”), testing is often permissible for safety-sensitive work—as part of a broader fitness-for-duty assessment, not as automatic discipline. Employers must still consider accommodation if a disability (addiction) is involved.

2) Return-to-work / monitoring

Following treatment for a substance-use disorder, targeted follow-up testing may be allowed (again, typically for safety-sensitive roles) where it’s part of an individualized plan that includes support and accommodation.

3) Specially regulated sectors

Some sectors (e.g., nuclear or similar high-security environments) have federal rules that expressly require fitness-for-duty programs with alcohol/drug components.

When testing is hard to justify

Random testing

“Fishing-expedition” or random testing is exceptional. In unionized settings, Canada’s top court says employers must prove a demonstrable workplace substance problem in a dangerous environment and still show that random testing meaningfully improves safety compared to less-intrusive measures. In non-unionized settings, Ontario cases distinguish alcohol (breath testing can indicate present impairment, sometimes justifiable in safety-sensitive roles) from most drug tests (often detect past use, not impairment). Either way, the bar is high.

Pre-employment screening

Testing before a job offer (or as blanket “screening”) is generally not permitted in Ontario because it can reveal disability information and lead to discrimination. Even post-offer testing for a safety-sensitive job is risky and discouraged unless it’s demonstrably necessary and tightly designed.

Cannabis changed the law… less than you think

Recreational legalization did not create a right to be impaired at work. Medical cannabis may require accommodation (like any medication that could impair), but employees must still perform work safely. Policies should focus on impairment and risk, not morality or off-duty use.

Privacy & confidentiality aren’t optional

Test results are medical information. Access should be strictly limited, securely stored, and used only for fitness-for-duty and accommodation—not broadly shared. Mishandling results can create privacy liability (and trust problems) even if a policy is otherwise lawful.

Union vs. non-union: similar principles, different routes

• Unionized workplaces: arbitrators apply a balancing of safety vs. privacy; random testing usually fails without clear evidence of a problem and strong safety rationale.

• Non-unionized workplaces: human rights analysis asks whether testing is a bona fide (legitimate) job requirement that’s reasonably necessary and minimally impairing, with accommodation up to undue hardship.

What to do if you’re told to take a test

1. Ask why (politely). Is this reasonable cause, post-incident, return-to-work, or random?

2. Clarify your role. Is your job truly safety-sensitive?

3. Request the policy and how results will be used, stored, and who will see them.

4. Consider accommodation. If addiction or a related health issue is in play, say so—your rights are protected, and accommodation should be discussed.

5. Don’t go it alone. A quick call with an employment lawyer can help you avoid missteps—especially before refusing a test or signing consents you don’t understand.

Bottom line for Ontario employees

Your employer can’t impose drug/alcohol testing whenever it wishes. Testing must be justified by real safety needs, carefully targeted, respectful of privacy, and paired with accommodation where disability is involved. Random or blanket testing is rarely justified. If you’re facing a test—or consequences for refusing—talk to us. Vanguard Law helps employees navigate these issues strategically and discreetly.