Dismissed for failing to complete drug treatment: a conduct decision that was fair
A Customer Services Supervisor for London Underground was fairly dismissed after being discharged from residential drug rehabilitation for threatening behaviour. The tribunal found the employer's investigation and decision were within the range of reasonable responses.
1 min read · Last updated 18 May 2026
Case details
- #drug-addiction
- #zero-tolerance-policy
- #safety-critical-role
- #residential-rehabilitation
- #gross-misconduct
- #conduct-dismissal
Key facts
- The claimant was employed as a Customer Services Supervisor, a safety critical role, and was addicted to cocaine.
- The respondent referred the claimant to its in-house Drug and Alcohol Assessment and Treatment Service (DAATS) and funded residential rehabilitation at Bosence Farm.
- The claimant signed a treatment agreement stating that failure to complete treatment could result in dismissal.
- The claimant was discharged from Bosence Farm before completing treatment due to escalating behaviour and a threat to hit another peer.
- The respondent investigated, held a disciplinary hearing, and summarily dismissed the claimant for gross misconduct.
- The claimant's appeal was dismissed after a further hearing.
Timeline
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Claimant discloses cocaine use
The claimant told the respondent's Occupational Health Counsellor that he had started using cocaine while off sick and was still using it.
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Claimant stood down from duties
The claimant was stood down from his safety critical role pending assessment.
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DAATS assessment begins
The claimant signed an assessment agreement with DAATS and began attending assessment groups.
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Treatment agreement signed
The claimant signed the DAATS Treatment Agreement Contract, agreeing to attend Bosence Farm residential rehabilitation from 18 January to 12 April 2021.
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Claimant enters residential treatment
The claimant started residential treatment at Bosence Farm in Cornwall.
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Written warning at Bosence Farm
The claimant received a written warning for dishonest and intimidating behaviour after an altercation with a female peer.
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Altercation with peer CD
The claimant had an altercation with another resident, CD, in the kitchen. The claimant later called the police alleging assault and belittling of his faith.
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Claimant asked to leave Bosence Farm
Bosence Farm staff decided to discharge the claimant due to escalating behaviour, including a threat to hit another peer, and lack of willingness to take responsibility.
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DAATS discharge letter
DAATS formally discharged the claimant, stating he was in breach of the treatment agreement and that they could not recommend safe reinstatement.
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Summary dismissal
After a disciplinary hearing and appeal, the claimant was summarily dismissed for gross misconduct for failing to complete the DAATS treatment.
The legal issue
The tribunal had to decide whether the employer had a fair reason to dismiss (conduct) and whether the dismissal was fair under section 98(4) of the Employment Rights Act 1996, considering whether the investigation was reasonable and whether dismissal was within the band of reasonable responses.
The outcome
The tribunal dismissed the claimant's complaint of unfair dismissal.
Key reasons:
- London Underground genuinely believed the claimant had committed misconduct by failing to complete the DAATS treatment, which he had agreed to.
- The employer carried out a reasonable investigation, including speaking to Bosence Farm staff and reviewing the treatment agreement.
- Dismissal was within the range of reasonable responses, especially given the safety-critical nature of the role and the zero-tolerance policy.
No compensation was awarded as the claim was unsuccessful.
Lessons & takeaways
- If you work in a safety-critical role, your employer is likely to have strict policies on drugs and alcohol, and failing to comply with treatment agreements can lead to dismissal.
- Signing a treatment agreement that warns of dismissal for non-completion creates clear expectations; tribunals will enforce such agreements if the employee breaches them.
- Employers should investigate thoroughly before dismissing for conduct, including speaking to third parties like treatment providers, to ensure their belief is reasonable.
- Employees who are unrepresented may still succeed if the employer's process is flawed, but in this case the employer's process was found to be fair.
What this case shows in practice
This case illustrates how employers in safety-critical industries can fairly dismiss employees who fail to complete drug or alcohol treatment, even when the employer has funded that treatment. The claimant, a Customer Services Supervisor for London Underground, voluntarily disclosed his cocaine addiction and agreed to attend residential rehabilitation. He signed a treatment agreement that explicitly warned that failure to complete the programme could result in dismissal.
After being discharged from the rehabilitation centre due to escalating behaviour, including a threat to hit another resident, the employer investigated and dismissed him for gross misconduct. The tribunal found that London Underground had a genuine belief in the misconduct, based on a reasonable investigation, and that dismissal was within the range of reasonable responses.
What the employer did right
London Underground followed a clear process: it referred the claimant to its in-house Drug and Alcohol Assessment and Treatment Service, funded the residential treatment, and obtained a treatment agreement. When the claimant was discharged, it investigated by contacting the treatment provider and reviewing the incident reports. The disciplinary and appeal hearings were conducted, and the decision was made by managers who were not involved in the initial referral.
The tribunal noted that the employer's zero-tolerance policy and the safety-critical nature of the role meant that dismissal was a proportionate response. The claimant's argument that he was dismissed for a disability-related reason (addiction) was not pursued, as the discrimination claims were withdrawn.
Why this matters for similar claims
This case reinforces that employers can rely on conduct, rather than capability, when dismissing an employee who fails to comply with a treatment programme. It also shows that the 'band of reasonable responses' test gives employers considerable leeway, especially in safety-critical roles. For employees, it highlights the importance of adhering to treatment agreements and the potential consequences of non-compliance.
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