Detection vs Impairment: The Question Every Employer Should Be Asking

By David Bainbridge, Founder of First Cohort Incorporated Ltd and Creator of the Better Testing Approach.

When I speak to employers about workplace drug and alcohol testing, I often ask a simple question:

"What are you actually trying to achieve?"

Most people initially answer, "We want to know if someone has taken drugs."

But after a bit more discussion, the real answer usually becomes clear.

What they actually want to know is whether their employees are safe to work.

That is where one of the biggest misunderstandings in workplace drug testing begins.

Detection and Impairment are not the same thing.

One of the most common mistakes I see businesses make is treating drug detection and workplace impairment as if they are the same thing. They are not.

A workplace drug test can tell us that a substance may be present in someone's system. Depending on the substance involved and the testing method used, that substance may have been consumed hours, days, or even weeks earlier.

What a drug test cannot automatically tell us is whether the person is impaired at that moment, whether they are unsafe to carry out their role, whether the substance is affecting their judgement or reaction times, or whether there is a legitimate medical explanation for the result.

This distinction is becoming increasingly important as more organisations introduce workplace drug testing programmes, particularly in industries where health and safety are critical.

A Positive Test Does Not Always Mean Someone Is Unsafe.

This is often the point where people stop and think.

An employee could return a positive drug test result and still be perfectly capable of carrying out their role safely. Equally, someone could return a negative result and still be unsafe for work because they are suffering from fatigue, stress, illness, distraction, alcohol hangover effects, or side effects from prescription medication.

The purpose of a good workplace drug and alcohol testing programme should not simply be to identify substances. It should be to help employers make informed decisions about safety, risk and fitness for duty.

The Rise of Medical Cannabis and Prescription Medication.

This conversation has become even more important with the growing number of people prescribed medical cannabis in the UK, alongside a wide range of other prescription medications that can potentially affect workplace performance.

Employers are increasingly asking questions about whether an employee can safely work while prescribed medical cannabis, whether a positive result automatically means impairment, what their legal responsibilities are as an employer, and how they balance workplace safety with employee rights.

These are sensible questions. The challenge is that the answers are rarely straightforward.

In many cases, a positive or negative test result is only one piece of a much larger puzzle.

Why Employers Need to Look Beyond the Test Result.

A modern workplace drug and alcohol policy should never rely solely on the outcome of a test.

Instead, employers should consider the wider picture. They should look at the employee's behaviour, any observable signs of impairment, the type of work being carried out, whether the role is safety-critical, any declared medical conditions or prescribed medications, and the information gathered throughout the investigation process. They should also consider whether the individual may require support. A test result is valuable information, but it is not the entire story.

The Real Goal: Fitness for Duty

In my view, the future of workplace drug and alcohol testing is not simply about identifying substances. It is about understanding whether somebody is fit for duty.

Good employers do not invest in workplace testing because they want laboratory reports sitting in a filing cabinet. They invest in testing because they want to protect employees, reduce workplace accidents, improve workplace safety, meet their legal obligations, manage risk effectively and support staff who may be struggling.

Those goals are linked to impairment and fitness for work, not simply detection.

The Better Testing Approach

At First Cohort, we believe there is a better way.

I call it Better Testing.

Better Testing recognises that workplace drug and alcohol testing should be part of a wider strategy that includes education, manager training, clear policies, risk assessment, appropriate testing, professional support and fair decision-making.

Most importantly, it recognises that a positive result should not automatically end a conversation. It should start one.

By understanding the difference between detection and impairment, employers can make safer, fairer and more informed decisions that protect both the business and its people.

Final Thoughts

The next time you hear someone say, "The test was positive, therefore they must be impaired." Ask yourself whether that conclusion is actually supported by the evidence, because in many cases, it may not be.

The question employers should be asking is not, "Did they take something?"

The question should be, "Are they safe and fit to perform their role?"

Understanding that difference could be one of the most important improvements you make to your workplace drug and alcohol testing programme.

Need Help Reviewing Your Workplace Drug and Alcohol Testing Programme?

At First Cohort, we help businesses implement workplace drug testing, alcohol testing, impairment awareness training, workplace substance misuse policies and support pathways that focus on safety, fairness and compliance.

If you would like to review your current approach and see how the Better Testing model could benefit your organisation, get in touch for an informal discussion. We will happily talk through your current arrangements and help you determine whether your testing programme is truly achieving what you want it to achieve.