Ask Dave
Workplace drug and alcohol testing can get complicated very quickly.
This is where I answer some of the questions I'm regularly asked about workplace drug testing, impairment, medical cannabis, non-negative results, policies and substance misuse at work.
I'll keep the answers straightforward, practical and based on what I've learned from working in the industry.
Can't find the answer you're looking for? Ask me.
Does a non-negative drug test mean someone is impaired?
No. A drug test can tell you that a substance, or its metabolites, has been detected above the test's cut-off level. It doesn't automatically tell you whether that person was impaired when the sample was taken.
That's one of the most important differences for employers to understand.
What should happen after a non-negative workplace drug test?
Don't jump straight to conclusions.
What happens next will depend on the type of test, your workplace policy, the circumstances surrounding the test and whether further laboratory analysis is required.
A non-negative screening result is information. What you do with that information matters.
What happens if an employee has a medical cannabis prescription?
A prescription doesn't mean an employer should ignore safety concerns, particularly in safety-critical work.
But detecting THC doesn't automatically prove current impairment either.
The prescription, the employee's role, potential side effects, workplace risks and your existing policies all need to be considered before deciding what happens next.
Can an employee refuse a workplace drug or alcohol test?
They can refuse to provide a sample, but that doesn't necessarily mean there won't be consequences.
Consent, your workplace policy, the employee's contract, the reason for testing and how the employer responds can all matter.
This is exactly why businesses need to think about these situations before they happen.
Can someone test negative and still be impaired?
Potentially, yes, testing has limitations. The substance involved, type of sample, detection window, cut-off level and timing can all affect what a test tells you.
A test result should be considered alongside other circumstances rather than treated as the entire answer.
What's the difference between a screening test and a laboratory-confirmed result?
An initial workplace screening test can produce a negative or non-negative result.
A non-negative screening result isn't the same thing as a laboratory-confirmed positive result.
Where confirmation is required, the sample should follow the appropriate chain-of-custody and laboratory process.
Can prescription medication cause problems at work?
Yes, potentially. A medication can be completely lawful and still affect someone's ability to perform certain tasks safely. The important question isn't simply “Is this medication prescribed?” It's whether it could create a workplace risk and how that risk should be managed.
Should someone automatically lose their job after failing a drug or alcohol test?
I don't believe failure should automatically mean fire.
There will be situations where immediate safety action is necessary, and there may be circumstances where disciplinary action is appropriate.
But a result doesn't tell you the whole story. Where it's safe and appropriate, I believe employers should also consider education, support and rehabilitation.
That's a big part of why I developed the Better Testing pathway.
Got a question about workplace drug and alcohol testing, impairment, medical cannabis or substance misuse at work?
Send it to me below.
If it's something I can help with, I'll get back to you. Your question might also become a future Ask Dave answer or video. However, I won't identify you or your business without your permission.