Ward manager unfairly dismissed after employer mistook cannabis metabolite for cannabis
A 40-year nursing veteran was unfairly dismissed by Priory Healthcare after the employer mistakenly believed a urine test showed she was under the influence of cannabis at work. The tribunal found the dismissal was outside the range of reasonable responses.
1 min read · Last updated 18 May 2026
Case details
- #cannabis-use
- #urine-test
- #metabolite-misunderstanding
- #gross-misconduct
- #polkey-reduction
- #contributory-conduct
- #acas-code
Key facts
- The claimant, a ward manager with 40 years' nursing experience, was dismissed after a urine test showed a metabolite of cannabis.
- The respondent believed the claimant had cannabis in her system and was under its influence at work.
- The test detected THC-COOH, a cannabis metabolite, not cannabis itself, but the respondent mistakenly treated it as cannabis.
- The claimant admitted using cannabis recreationally every night, but denied being under the influence at work.
- The tribunal found the respondent did not have reasonable grounds for its belief and the dismissal was unfair.
- The claimant's wrongful dismissal claim succeeded as there was no repudiatory breach of contract.
Timeline
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Employment started
Mrs Fermin began working for Priory Healthcare Limited as a ward manager.
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Last cannabis use before test
The claimant last used cannabis recreationally with a friend on this date.
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Drug test conducted
The claimant was asked to provide a urine sample after anonymous allegations of drug use. She admitted using cannabis and was suspended.
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Investigation call
Mr Rice-Thompson spoke to the claimant about her cannabis use and the test results.
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Investigation report
Mr Rice-Thompson concluded there was a case to answer for attending work under the influence of cannabis.
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Disciplinary hearing
Mr Graham held a disciplinary hearing and dismissed the claimant without notice for gross misconduct.
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Appeal hearing
Miss Jackson heard the claimant's appeal and upheld the dismissal.
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Appeal outcome letter
Miss Jackson confirmed the dismissal was upheld.
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Tribunal hearing (day 1)
The employment tribunal heard evidence from the claimant and respondent witnesses.
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Tribunal hearing (day 2)
The tribunal concluded the hearing and reserved judgment.
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Judgment issued
Employment Judge Aspden found the claimant was unfairly dismissed and wrongfully dismissed.
The legal issue
The tribunal had to decide whether the employer had reasonable grounds to believe the claimant was under the influence of cannabis at work, and whether the dismissal for gross misconduct was fair and lawful.
The outcome
The tribunal found that the claimant was unfairly dismissed and wrongfully dismissed.
The key reason was that the employer misinterpreted the drug test results. The test detected THC-COOH, a cannabis metabolite that can remain in the body for weeks, not the active drug. The employer mistakenly believed the claimant had cannabis in her system and was under its influence at work, but the tribunal found this belief was not reasonable.
The remedy will be determined at a separate hearing. However, the tribunal indicated that any compensation will be reduced by:
- 50% for a Polkey reduction (chance of dismissal even with fair process)
- 40% for contributory conduct (the claimant's admitted recreational cannabis use)
Lessons & takeaways
- Employers must understand the difference between drug metabolites and active drugs before relying on test results for dismissal.
- A long-serving employee with a clean record is entitled to a thorough investigation and fair process before being dismissed for gross misconduct.
- Admitting to off-duty drug use does not automatically justify dismissal for being under the influence at work.
- Tribunals will scrutinise whether the employer had reasonable grounds for its belief, not just whether the employee actually committed the misconduct.
A costly misunderstanding
A ward manager with 40 years' nursing experience was dismissed by Priory Healthcare after a urine test detected a cannabis metabolite. The employer believed she had cannabis in her system and was under its influence at work. However, the test detected THC-COOH, a metabolite that can remain in the body for weeks after use, not the active drug. The tribunal found the employer's belief was not reasonable, making the dismissal unfair.
What could have been done differently
Priory Healthcare could have avoided this outcome by properly understanding the drug test results. The claimant admitted using cannabis recreationally every night, but denied being under the influence at work. The employer should have sought expert advice on the test results and considered whether the claimant was actually impaired. Instead, they jumped to conclusions based on a misunderstanding of the science.
Why this matters
This case highlights the importance of employers having reasonable grounds for their beliefs when dismissing for conduct. A genuine but mistaken belief is not enough if it is not based on reasonable grounds. The claimant's long service and clean record also counted against the employer. The case serves as a warning to employers not to overreact to drug test results without proper interpretation.
The remedy hearing will determine compensation, but the tribunal has already indicated significant reductions: 50% for the chance of dismissal even with fair process (Polkey reduction) and 40% for the claimant's own conduct in admitting recreational cannabis use.
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