Detection Isn’t Impairment and Getting This Wrong Causes Problems.

One of the biggest misunderstandings I see in workplace drug and alcohol testing is the belief that a positive test automatically means someone is unsafe to work.

It doesn’t.

A drug test tells you that something is present. It doesn’t tell you how someone is functioning at that moment. That distinction matters more now than ever, particularly with prescribed medications and changing attitudes towards substance use.

Where businesses run into trouble is when testing replaces judgement instead of supporting it.

I’ve seen situations where someone was removed from work purely because of detection, despite showing no signs of impairment. I’ve also seen the opposite, where someone was clearly unfit for work but no action was taken because a test hadn’t yet been completed.

Neither approach protects safety.

Impairment is about what you can see. Changes in behaviour, coordination, decision-making, or awareness. Managers don’t need to diagnose anything, but they do need confidence in recognising when someone is not safe to continue working.

The organisations that get this right understand that testing is one part of a bigger system. Observation, conversation, policy, and support all sit alongside it.

When detection and impairment are understood properly, decisions become fairer, safer, and far easier to manage.

That’s where most workplaces want to get to.