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Medicinal Cannabis and Employment Law

Two years ago, when New Zealand was considering its position on legalising cannabis, I wrote a blog post called: "Let's talk: Cannabis and Employment Law." While the referendum wasn't ultimately successful, this blog post has assisted many in navigating their rights with respect to the use of medicinal cannabis and their employment.

The purpose of this blog post is to expand on my prior blog post, providing a more in-depth analysis of the current law with respect to medicinal cannabis in the workplace. While there have been no cases before the Employment Relations Authority regarding the use of prescription medicinal cannabis in the workplace, the idea of medicinal cannabis was a concept I explored in PEX v Lyttelton Port Company, after my client tested positive for THC after using cannabis for medicinal purposes. While we were ultimately unsuccessful, this case does provide us with some stepping stones, which can assist in building our understanding about the law as it currently stands, and the space for growth in this area.

Obligations to Disclose

If you have an active prescription for medicinal cannabis, you may be required to disclose this to your employer, even if your employer doesn't conduct routine drug and alcohol tests. An employee is required to disclose any health condition, or prescription, that has the potential to impact their ability to perform the tasks and duties associated with their role, or which has the potential to create a risk to health and safety.

It will be a case-by-case analysis about whether disclosure is necessary, and will largely depend on the type of the job being performed, the nature of the prescription, the employee's use of the medication, and whether the employer has existing drug and alcohol policies.

If an employee is using CBD oil in the evenings, and is an office worker, there will unlikely be an obligation to disclose, because this prescription is unlikely to impact their ability to perform the tasks and duties associated with their role, and unlikely to create a risk to health and safety.

However, on the other end of the spectrum, if an employee is using medicinal cannabis which includes both CBD and THC routinely, and they work in a safety sensitive role, they will likely be required to disclose their medication.

If you're unsure, I recommend that you seek legal advice first, and potentially consult with your doctor (as you'll read below).

Medicinal Cannabis and Impairment

The first thing to understand about the use of medicinal cannabis in the workplace, is the employer's concern for impairment. In this sense it is important to highlight that it is not true that the only way for an employer to confidently exclude impairment is with a negative urine drug test. Drug tests are designed to detect a metabolite of cannabis, which means that it is possible for a person to be intoxicated and return a negative result for THC. In evidence provided in PEX, it was conceded that it can take between 2 to 8 hours to turn a urine test positive for non-cannabis users.

I further argued that it was not true that any level of the THC metabolite in the bloodstream inherently presents a risk to health and safety. I made the point that many people have prescriptions for medicinal cannabis, myself included, and who are legally able to continue to drive their vehicles, notwithstanding the fact that they would likely fail a drug test. I argued that, while I appreciate the safety sensitive nature of Lyttelton Port Company (and other companies who impose drug testing policies), when it comes to medicinal cannabis, what makes the activities at Lyttelton Port Company significantly more dangerous than driving?

I argued that, ultimately, in accordance with the Health and Safety at Work Act 2015, an employer is required to minimise risks to health and safety as far as is reasonably practicable, and that a strict approach to drug testing falls short of this approach. In my view, while drug testing shows that a person has the cannabis metabolite in their system, an employer must go further to ascertain impairment. Drug testing is only one tool in the toolbox, and it's not the most effective tool for limiting the risks of impairment in the workplace.

Because the truth is, having a zero-tolerance approach to cannabis does not stop cannabis in the workplace: it makes employees better at hiding it. It makes employees consider other recreational drugs, which may not show on a drug test, such as micro-dosing on LSD or psilocybin (magic mushrooms).

Unfortunately, this argument did not sway the Employment Relations Authority, with their response being:

[82] ... There is no evidence that shows an employee who consumes medicinal cannabis is not impaired – just because it is legitimately prescribed does not mean the employee can consume it and assume they are not impaired. The risk remains the same for an employer and a positive test result arising out of consumption of medicinal cannabis is likely to be a breach of the relevant drug and alcohol policy with the prescription being a factor for the employer to consider

Human Rights Lens

While I accept that medicinal cannabis presents challenges in the workplace, these challenges are no different to an employee who is prescribed opiates, benzodiazepines, methylphenidate and other medication which has the potential to impair and employee in the workplace.

Many will be unaware that benzodiazepines, such as diazepam and clonazepam, are detectable in a urine test for between 1 day to 6 weeks after ingestion. This means that, even if an employee is using prescription benzodiazepine's in the evenings to relieve anxiety and/or chronic pain (as examples), the employee will return a positive test during the working day. Why then do benzodiazepines receive such little attention in the 'health and safety' space compared to medicinal cannabis?

This argument couldn't be teased out in PEX, as PEX did not have a prescription for medicinal cannabis at the time of the termination of his employment, and the fact that he later received a prescription was of little relevance to the Authority's investigation: the Authority is required to consider whether the employer's actions at the time of termination were what a fair and reasonable employer could do. However, the Authority did make this comment:

[82] ... In this case the Policy deals with “Legal Medications” and “Drugs at Work”. An employee who takes prescription medication must check with their Doctor or Pharmacist about any side effects from the medication that could be a risk in their work and then notify their manager if there are side effects so that LPC can take a view on mitigating any risk, including getting an opinion from a Medical Review Officer. This must apply to medicinal cannabis so if properly applied it is likely that an unfair sanction in relation to consuming medicinal cannabis would not occur because specific arrangements would be in place for that employee.

This means that if you're concerned about your rights regarding medicinal cannabis in the workplace, you will first want to consult any policies regarding prescription medications. If your employer does not have a specific policy, you may want to ask for their position on prescription medication which has the potential to cause impairment.

I imagine that, in most cases, the next step would be to obtain good medical information from your doctor regarding the prescription for medicinal cannabis. You would want this medical certificate to outline your prescription, your use of the medication, the potential for impairment, and the potential for this medication to impact your employment.

You would then use that medical certificate to have constructive conversations about your ability to continue in employment. If you get to this point, you may want to consider legal representation. If you can't afford legal representation, please contact me for some free advice on your next steps.


In my view, the introduction of medicinal cannabis calls for a reconsideration to the way in which employment law views and applies drug testing policies: a fair and reasonable employer could not have differential outcomes for employees depending on their reasons for taking cannabis. In my view, it is not relevant how the drugs entered the employee's system; the only relevant consideration is that which interacts with the Health and Safety at Work Act 2015.

While the Authority stated that my "general argument based on impairment is compelling," the law remains that an employer is able to continue to take a harsh approach to drug testing. I am sure that, as prejudices against cannabis change, we will similarly see a shift in drug testing practices.

How long will that take?

How long is a piece of string?


Legal AF Limited t/a Ashleigh the Advocate


Help me, help others: your contributions allow me to continue creating substantial blog posts like these.

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