Train driver dismissed after positive cannabis test: zero-tolerance policy upheld

When a positive drug test ends a career

This case shows how a single random drug test can unravel a long career, even when the employee genuinely believes they have done nothing wrong. The claimant, a train driver with 10 years' service, tested positive for cannabis metabolites at nearly five times the industry cut-off. He insisted the result came from CBD oil he was using for arthritis pain, not from cannabis itself. But without independent evidence to back that up, the tribunal accepted the employer's version of events.

What the employer did right

Arriva Rail London followed a thorough process. The test was conducted by an accredited tester, the result was confirmed by a qualified Medical Review Officer, and the claimant was given the opportunity to have the 'B' sample tested independently — which he declined. The investigation and disciplinary hearing were properly carried out, with union representation throughout. The employer also considered the claimant's medical explanations but found no evidence to support them. For a safety-critical role like train driving, the tribunal said the decision to dismiss was within the range of reasonable responses.

What the claimant could have done differently

The claimant's main weakness was his inability to provide any independent evidence. He did not produce the CBD oil bottle or its ingredients, nor did he obtain a medical opinion to support his claim. If he had done so, the outcome might have been different. The tribunal noted that the claimant's own medical records did not mention cannabis use or CBD oil, and the medical review officer had already considered and rejected the possibility that CBD oil could cause such a high level of THC metabolites.

Why this matters

This case is a reminder that in safety-critical industries, employers are entitled to rely on accredited test results and to enforce strict drug policies. Employees who use over-the-counter products like CBD oil must be aware of the risks. The tribunal also rejected the disability discrimination claim, finding that the claimant's osteoarthritis did not meet the definition of disability under the Equality Act 2010 at the relevant time, and that in any event the employer did not know about it. For anyone considering a similar claim, the key lesson is that a fair process and credible evidence are essential — both for the employer defending a dismissal and for the employee challenging it.