Three months after we implemented their random testing programme, an HR manager called me. Not to book another round of tests. To ask if we still had the documentation from their last screening.

An employee had failed a test. Then challenged the dismissal. Now their solicitor was asking questions the HR team couldn't answer.

Most HR managers think having a random testing policy means they're protected. You've got the right intent. You're following best practice.

You've even budgeted for quarterly screenings.

But intent doesn't stand up in a tribunal.

The employee's solicitor asked four questions. Only one was about whether the person had drugs in their system. The other three were about the process, the equipment approval status, and whether the policy had been applied consistently. The HR team could answer one question confidently.

That's the pattern I see most often. Well-intentioned screening programmes that look comprehensive until someone challenges the result. Then

the gaps appear.

Where policies unravel

It's not usually the testing itself that creates the legal exposure. It's what sits around it.

I've reviewed dozens of policies over the years. Most cover the obvious parts - when you'll test, what happens if someone refuses, what constitutes a positive result. The problems show up in the detail no one thinks to document.

Like whether your provider's equipment is Home Office approved. Sounds technical, and it is, but that approval status matters when you're defending a dismissal. An employee's solicitor will ask about calibration, accuracy rates, whether the device meets recognised standards. If your provider can't evidence that, your entire testing programme becomes questionable.

Or how you selected people for random testing. Actually random, or did a manager pick names? There's case law around selection methodology. Tribunals want to see systems, not judgment calls.

Or whether the person conducting the test had proper training. Not just "knows how to use the device" training. Training in confidentiality, data handling, what to do if someone becomes distressed. The process around the test matters as much as the result.

We see this with clients who switch to us from cheaper providers. They thought they were getting the same service. Then they see what comprehensive screening actually involves - the documentation, the audit trail, the equipment approval, the confidentiality protocols. Most of them had no idea these elements were missing from their previous arrangement.

The consistency question

Here's where most policies fall apart: inconsistent application.

You test the warehouse team quarterly but the office staff never. You always test after incidents in the depot but not in the yard. You brought in random testing two years ago but three long-serving employees have never been selected.

Each of those creates a defence for an employee facing dismissal. Their solicitor will argue discriminatory application. They'll point to the people who weren't tested. They'll question why the policy applied to their client but not to others.

I worked with a transport company last year. They'd tested a driver after a minor collision - completely reasonable, their policy covered post-incident screening. Driver tested positive, they dismissed him. He claimed the collision was the excuse, not the reason. Said they'd wanted him gone for months.

Turned out they'd had six other minor incidents that year. None of the other drivers had been tested.

The company had followed their policy for that incident. But they hadn't followed it consistently across all incidents. That inconsistency cost them the tribunal, plus a settlement I'm not allowed to mention the size of.

What actually protects you

A random testing policy protects you legally when it does three things well.

First, it uses equipment and processes that can be evidenced if challenged. Home Office approved equipment. Proper chain of custody. Documentation that shows exactly what was tested, when, by whom, and what the result meant.

Second, it's applied consistently. Everyone who should be in the testing pool is in it. Everyone selected actually gets tested. Every positive result triggers the same process. No exceptions based on tenure, role, or whether someone's having a difficult time.

Third, it's supported by training and awareness. Your managers understand what the policy says and why it matters. Your employees know they might be tested. The person conducting tests knows how to handle the process professionally. Not just you hoping everyone roughly knows what they're doing.

We build all three elements into the programmes we design. Not because we're perfectionist but because we've seen what happens when any one element is missing. One gap is all it takes when someone challenges a result.

The question to ask your provider

If you've got a random testing policy in place, ask your provider one question: "If this result goes to tribunal, what documentation can you provide?"

If they pause, or mention just the test result itself, that should concern you. You need the equipment approval certificate. The calibration records. The tester's training credentials. The chain of custody documentation. The policy compliance checklist.

That's not paranoia. That's what employment solicitors ask for when they're building a defence.

Most providers will give you a test result - positive or negative. The good ones will give you everything you'd need to defend that result in court. There's a significant difference between the two, and you usually don't discover which one you've got until you're sat across from a solicitor trying to defend a dismissal.

Many years of doing this work, that's the conversation I least want clients to have without the right documentation behind them.

If you're not certain what your current provider would give you under tribunal scrutiny, that's worth finding out before you need it. We can review what you've got in place - what would hold up and what needs strengthening. Doesn't require changing everything, but it might require changing something.

Better to know now than when someone's solicitor starts asking questions you can't answer.