Medicinal cannabis and your job: drug testing and your rights

After driving, work is the thing medicinal cannabis patients worry about most, here is what you need to know:

The short version

• A prescription may not override your employer's drug and alcohol policy.
• Workplace urine testing detects cannabis for days to weeks after use, far longer than roadside saliva testing.
  
• Whether a patient can be disciplined for a positive test in a job with no safety risk is untested in New Zealand.
• Our view: do not raise it with your employer unless there is a reason to, such as testing in your workplace or an incident.

Workplace testing is not roadside testing

This trips people up constantly, because the two got conflated in the coverage of the 2025 drug driving law.

Roadside testing uses oral fluid. It looks for recent use, and detection windows are commonly cited as somewhere around 8 to 12 hours, longer for frequent users.

Most workplace testing in New Zealand uses urine, under the standard AS/NZS 4308. Urine testing does not look for THC itself. It looks for THC metabolites, the inactive compounds your body produces as it processes cannabis and then excretes over time. Those hang around for days after a single use and can persist for several weeks in someone using daily.

The practical consequence: you can be stone cold sober, entirely unimpaired, days past your last dose, and still fail a workplace urine test. The test is not measuring impairment and does not claim to.

Some workplaces use oral fluid testing instead, under AS/NZS 4760, which has a shorter window. Worth knowing which one your employer uses.

Where the law sits

There is no neat answer here, and anyone who gives you one is overselling it.

Employers have duties under the Health and Safety at Work Act 2015 to manage risks, which is what drug and alcohol policies are built on. Employees have protections under employment law and the Human Rights Act, and there are arguments to be made about disability discrimination and about the reasonableness of a policy that treats a prescribed medicine as misconduct.

What there is not, in New Zealand, is a clear statutory rule saying a prescription exempts you from a workplace policy. Outcomes turn on the specific policy, the role, the industry, and how the employer handles it. Safety-sensitive work sits at one end. An office job with no testing regime sits at the other.

The honest answer: untested

As far as we are aware, no New Zealand court or Employment Relations Authority decision has squarely settled whether a prescribed cannabis patient can lawfully be disciplined or dismissed over a positive test. The medicinal scheme is only a few years old, cases take years to reach a determination, and the ones that might have set a precedent have generally settled instead. So the position is genuinely unresolved.

What can be said is that the strength of an employer's position varies enormously depending on the job.

In a genuinely safety-sensitive role, driving, heavy machinery, heights, working with patients, an employer has a real health and safety duty to point to, and a testing policy is much easier to justify. That is the end of the spectrum where an employer is on the firmest ground, and where you should be most careful.

In an ordinary office job with no identifiable safety risk, the employer's position is far weaker, and this is where the untested questions sit. A drug and alcohol policy is supposed to be reasonable and justified by an actual risk, not applied simply because it exists. It is not obvious what risk is being managed by testing someone who sits at a desk. It is not obvious that lawfully taking a prescribed medicine outside work hours is misconduct. And if the underlying condition amounts to a disability, discrimination and reasonable accommodation arguments come into play.

Those are decent arguments. They are not a guarantee, and nobody can tell you how they would run, because they have not been run.

Which cuts both ways. If you are in a low-risk role and this happens to you, you may have a stronger case than your employer expects. You would also be the test case, with everything that involves: time, cost, stress and an uncertain outcome. That is a real consideration and it is a reason to be careful about what you disclose and to whom, not a reason to assume you have no rights.

If you are facing an actual disciplinary process, get advice from a union or an employment lawyer.

Should you tell your employer?

Our honest view: not unless there is a reason to.

Your prescription is private health information. You are generally not obliged to volunteer it, and disclosing it invites questions, assumptions and sometimes treatment you would rather not deal with. Plenty of patients have found that a disclosure made in good faith created a problem that did not previously exist.

The reasons to raise it:

• Your workplace tests. Pre-employment, random, post-incident or return-to-work. If testing is part of the job, a conversation before a positive result is far better than one after it.
• Your role is safety-sensitive. Driving, machinery, heights, health care. Talk to your prescriber first about whether and how to manage it.
• Something has happened. An incident, an accusation, a test you have been asked to take.

If none of those apply, there is usually nothing to be gained by raising it.

If you do need to have the conversation

1. Talk to your prescriber first. Ask specifically about your role, your dose and your timing. Their answer matters and their support matters.
2. Read the policy before you say anything. Employers must make their drug and alcohol policy available. Find out what triggers a test, what the process is after a positive, and whether prescribed medicines are addressed at all. Many policies have a section on prescription medication that nobody has ever applied to cannabis.
3. Get a letter. A letter from your prescriber confirming you are under treatment, without necessarily detailing your condition, is far stronger than telling someone verbally. Calyx Clinic patients can request one by emailing support@calyx.clinic.
4. Frame it as management, not disclosure. You are telling them how the risk is being handled, not confessing to something.
5. Put it in writing. Follow up any conversation with an email summarising what was agreed. If it goes wrong later, that record is the most useful thing you will have.

Related

Roadside drug testing and medicinal cannabis covers the driving side, where a prescription does give you a medical defence against the infringement. How to get a prescription covers the process.

General information only. This is not legal, employment or medical advice. Employment outcomes depend on your specific policy and circumstances. If you are facing a disciplinary process, get advice from a union or an employment lawyer.