What the McCarthy tribunal decision really says about medical cannabis, driving and work

At first glance, the tribunal decision in Miss L McCarthy v Kirklees Metropolitan Council looks like exactly the sort of case the medical cannabis community has feared: a patient has a lawful medical cannabis prescription, wants to return to work, and the outcome appears to suggest that medical cannabis use means you cannot safely work or drive as part of your job. Read through that lens, and reduced to a newspaper headline, it is easy to see why people are worried. But that is not what the tribunal actually decided.

The important distinction is that the tribunal did not find that medical cannabis patients are automatically unfit for work or unable to drive. It found that, in this particular situation, the employer was entitled to pause and seek further information before allowing a full return to normal duties, because the job involved vulnerable service users and some driving, and because the employer did not yet have enough role-specific and prescription-specific information to complete its safety assessment.

The claimant had a diagnosis of Emotionally Unstable Personality Disorder / Borderline Personality Disorder, which the employer knew about. She had also experienced a serious mental-health crisis in September 2023, had been admitted to psychiatric hospital, and was absent from work.

During this period, she also disclosed previous illegal drug use, including cocaine and cannabis. She later obtained a private medical cannabis prescription, and provided her employer with some information about medical cannabis, including clinic correspondence and external guidance.

At around the same time, the employer received a PIPOT safeguarding referral involving alleged aggressive or threatening behaviour reported through NHS and police channels. Because the claimant worked with vulnerable service users, the employer treated this as a significant safeguarding issue and required a further enhanced DBS check.

So the tribunal was not looking at a simple question of "can someone prescribed medical cannabis work and drive?" It was looking at a much narrower question: was this employer acting unlawfully when it paused, asked for more information, sought occupational-health advice, considered safeguarding concerns, and managed a staged return to work in this specific set of circumstances? The tribunal answered no.

A central concern is that the decision might create a precedent that employers can say "there is not enough information about medical cannabis, so we cannot safely let you drive." But that is not what the tribunal found.

The claimant alleged that she was told in April 2024 that she could not drive as part of her duties. The tribunal rejected that allegation. It found that no driving prohibition was imposed. There had been discussion about medical cannabis, driving law, and the statutory defence where medication is prescribed and taken as directed, but the tribunal found the employer did not ban her from driving.

That is important. The case does not stand for the proposition that an employer can automatically prevent a medical cannabis patient from driving for work. It stands for the much narrower proposition that, where there are specific safety-related questions, an employer may ask for relevant information before reaching a decision.

UK driving law also does not impose a blanket ban on people taking prescribed medicines. GOV.UK explains that a person may drive after taking certain prescribed medicines if they have been prescribed them, have followed healthcare advice, and the medicine is not causing them to be unfit to drive.

The claimant argued that the employer had no business asking about her driving while taking prescribed medication, and that other medicines were not treated in this way.

The tribunal rejected that argument. It accepted evidence from HR that similar enquiries would be made if any employee's prescribed medication was suspected to affect their ability to perform their duties safely.

This is the crucial distinction. The tribunal did not say "medical cannabis is uniquely risky, so employers can restrict it." It said, in effect, if any medication may affect safe performance in a particular role, the employer can make proportionate enquiries.

That matters because many prescribed medicines can affect driving, judgement, alertness, coordination, or reaction time, for example opioids, benzodiazepines, sedatives, strong painkillers, some psychiatric medications, and other controlled medicines. GOV.UK's drug-driving guidance is framed around impairment and prescribed medicines generally, not medical cannabis alone.

The problem would be different if an employer scrutinised medical cannabis patients but ignored comparable risks from other prescribed medicines. That could potentially support an argument of inconsistent or discriminatory treatment. But on the evidence in this case, the tribunal accepted that the employer's approach was medication-risk based, not cannabis-stigma based.

The tribunal found that the claimant had provided some information, but not enough specific information for the employer to complete its assessment.

She had sent a letter from a private clinic, screenshots of extracts from DVLA guidance, and general employer guidance about medical cannabis. However, the tribunal described some of this material as selective and said no sound decision could be made on extracts and the claimant's own views alone.

The employer wanted more specific information about the claimant's actual prescription. The tribunal noted that as late as 29 February 2024, Ms Pickering had written asking for details of the prescription, but those details were not provided.

The missing information appears to have included:

• the precise prescription details;
• formulation and product type;
• dose and frequency;
• timing of use;
• route of administration;
• whether the dose had changed;
• prescriber guidance on driving;
• whether the medicine could affect cognition, decision-making, coordination, reaction time, or safe service delivery.

The tribunal also referred to a clinic letter from Dr Hazlett of Curaleaf, concerning an appointment on 25 March 2024, which included advice that driving should be avoided at certain times when using the prescription, including after a dose change until the patient knew how the medicine affected them. The tribunal said this was information the employer was entitled to receive because the claimant drove during work and occasionally transported service users.

This is one of the most important lessons from the case. The issue was not simply whether medical cannabis was lawful. The issue was whether the employer had enough patient-specific, prescription-specific and role-specific information to assess safe working and driving.

A major reason this case became difficult was that occupational health did not give the employer a clear, role-specific answer on medical cannabis, driving and safe working. An occupational-health physician had previously reported that the claimant was fit to return to work with advice, but that report made no reference to her prescribed cannabis and stated that she was not on active treatment. The tribunal found that this left an obvious gap, because the employer knew medical cannabis had been raised but did not yet have occupational-health advice on its impact on driving, cognition, safeguarding duties, or safe service delivery.

That gap became more significant because the claimant's role was not a purely office-based role with no wider risk. She worked with vulnerable service users and her duties involved some driving around the district, with occasional transport of service users. In that context, the employer was entitled to seek further occupational-health guidance rather than simply rely on a generic "fit to return" opinion that had not addressed the actual medication issue.

However, one part of the later occupational-health report needs careful handling. The report stated that "the fact a product is prescribed does not imply these risks are different to those of illicit cannabis." In a narrow pharmacological sense, there is a limited point here: delta-9-THC can potentially affect cognition, coordination, reaction time, judgement and driving safety, whether it comes from a lawful prescription or an illicit source. A prescription does not mean a person can drive or perform safety-sensitive work while impaired.

That sentence is incomplete, and potentially damaging, if treated as a workplace conclusion. Prescribed medical cannabis is not the same as illicit cannabis in any practical, clinical or regulatory sense. The correct lesson is therefore not that employers can treat lawful medical cannabis patients as illicit drug users. The correct lesson is that where a role involves driving, vulnerable people or safety-sensitive duties, the employer may need patient-specific and prescription-specific information before completing a safety assessment. That means looking at the actual prescription, dosage, timing of use, route of administration, stability on the medication, side effects, clinical advice, driving guidance and the duties involved.

This distinction matters because the occupational-health report did not conclude that the claimant was impaired. It said the practitioner could not objectively measure how the claimant was affected by THC and therefore could not comment on whether she could provide a safe service, including driving, while using medical cannabis. That is a much narrower point. It was not a finding that medical cannabis made her unsafe; it was a statement that occupational health did not have enough information to advise confidently.

That framing recognises the legitimate safety issue without collapsing lawful, supervised medical treatment into illicit drug use. The important point for employers is that uncertainty should not become a blanket ban. The proper question is not "this employee uses medical cannabis, so are they unsafe?" The proper question is: this employee is prescribed this medicine, at this dose, in this role, can they safely perform these duties, with or without reasonable adjustments?

For the medical cannabis community, the message is clear: yes, impairment must be taken seriously; no, prescribed cannabis should not be treated as equivalent to illicit cannabis; and no, employers should not use generic uncertainty about THC as a reason to exclude lawful patients from work or driving duties. The correct approach is individualised evidence, occupational-health assessment, prescriber guidance and proportionate risk management, not stigma, assumption or blanket restriction.

The decision should not be read as a green light for employers to impose blanket restrictions on medical cannabis patients. A blanket rule such as "you use medical cannabis, so you cannot drive or work in this role" would be very different from what happened here.

The safer and more lawful approach is individualised. Employers should ask:

1. What are the employee's actual duties?
2. Is driving or another safety-sensitive task involved?
3. What is the actual medication, dose, timing, and side-effect profile?
4. Has the patient recently changed dose?
5. What has the prescriber said about driving or impairment?
6. Does occupational health have enough information to advise properly?
7. Are there reasonable adjustments that would manage any risk?
8. Is the same approach being taken to other potentially impairing prescribed medicines?

For patients, the practical lesson is to avoid leaving an information vacuum. If a role involves driving, vulnerable people, machinery, safeguarding, clinical work, or safety-sensitive duties, it is sensible to provide:

The Independent's coverage is more than an oversimplification, it is materially inaccurate and socially irresponsible. Its headline frames the case as though a worker was stopped from driving simply because she was prescribed medical cannabis, and the article goes further by claiming that her case was dismissed because "no reasonable worker" would expect the council to allow her to continue working while taking medical cannabis.

That is not what the tribunal ruled. The tribunal did not find that medical cannabis patients cannot reasonably expect to work. It did not find that prescribed cannabis is inherently incompatible with driving. It did not endorse blanket workplace restrictions on lawful patients. In fact, the tribunal found that the allegation she had been told she could not drive was not established, that no driving prohibition was imposed, and that there was no policy of refusing to allow her to return to work because of her prescribed cannabis.

That is a dangerous distortion of the judgment. The tribunal's reasoning was about this claimant, in this role, against this factual background: vulnerable service users, a PIPOT safeguarding referral, incomplete occupational-health advice, recent serious mental-health concerns, previous disclosed illegal drug use, and missing prescription-specific information. It was not a ruling against medical cannabis patients as a whole.

A responsible report should have made that distinction clear. Instead, the framing risks handing employers a misleading soundbite they may wrongly use to justify blanket restrictions. That is not supported by the judgment. The lawful and sensible approach is individualised assessment: what is the medication, what are the duties, is the person impaired, what does the prescriber advise, and what reasonable adjustments or controls can manage any real risk. Anything less risks turning a nuanced tribunal decision into a weapon against patients who are using a lawful prescribed medicine.

What it does show is that, where a job involves vulnerable people and driving, and where there are wider health, safeguarding and information concerns, an employer may be entitled to ask for specific information before allowing a full return to normal duties.

The problem was not the existence of a medical cannabis prescription. The problem was the combination of safeguarding concerns, incomplete occupational-health advice, recent health issues, and missing prescription-specific information.

Engage with the correct process, provide the right evidence, address impairment honestly, and use risk assessments as a tool to enable work, not as a punishment or barrier.