Best practices for workplace drug screening and medicinal cannabis

“It’s a really untested area of law.”

So says Mike Mercer, Senior Associate at Simpson Grierson, in talking about medicinal cannabis and the workplace.

Cannabis is still an illegal drug but of course medicinal cannabis has been legalised, he says.

“I don't think a lot of employers have really turned their mind to this so it's going to generate quite a bit of case law.”

According to The Drug Detection Agency (TDDA) in New Zealand, even for employees in safety sensitive industries, there has been a rise in cannabis use. Cannabis contains THC, which is a psychoactive component capable of impairing cognitive functions and motor skills. Even if prescribed, TDDA warns it can affect an employee’s ability to safely carry out their work.

Unlawful or lawful use of cannabis?

The Medicinal Cannabis Scheme came into effect on 1 April 2020 with the commencement of the Misuse of Drugs (Medicinal Cannabis) Regulations 2019. The scheme gives access to medicinal cannabis products for patients via prescription from a doctor.

The difficulty for workplace drug testing for THC is that it doesn’t decipher whether it was in the system through lawful or unlawful use, says Mercer.

“Drug testing as we have it to date only shows whether or not someone has THC or any other type of drug that they’re testing for in the system,” he says. “It can’t help the employer determine whether or not the employee is impaired at the time that drug test is taken. Cannabis can stay in someone’s system for three to four weeks.”

This causes a number of issues, especially because an employer has competing obligations, says Mercer.

“They have to be a fair and reasonable employer under the Employment Relations Act 2000, but they also have a duty under the Health and Safety at Work Act to ensure the risks of harm in the workplace have been eliminated,” he says.

Safety sensitive industries and cannabis

For employers that traditionally work in industries with safety sensitive areas, for instance with heavy equipment, those obligations need to be taken seriously, says Mercer.

“They can put in place reasonable drug testing policies to ensure their employees are not under the influence of drugs and alcohol that could cause harm in the workplace.”

This isn't just an issue with medicinal cannabis, he says. “Similar issues arise from employees that may have ADHD or other types of neurological disorders, that could be taking controlled medication.”

The implications for those whose operations involve safety sensitive roles are significant, he says.

“Employers that have a high risk of harm in the workplace are more likely than not to be justified in taking a zero-tolerance approach and to require drug testing in the workplace.”

Employers need strong justification for drug testing

Not every employer is going to be able to justify having a zero-tolerance drug and alcohol policy or a random drug testing policy in the workplace though, advises Mercer.

“It’s quite an intrusive policy so the employer needs to have a strong justification. For office-based workers, it’s unlikely that having a blanket random drug testing policy is going to be justified on a carte blanche basis.”

So what's the best way for an employer to protect itself against potential problems?

“Firstly, going back to the employer’s good faith obligations, they would need to have a robust drug and alcohol policy in their workplace,” says Mercer.

“They also need to have a contractual basis for it - so have that in the employment agreement. If they're going to require drug and alcohol testing, or drug testing, then they need to clearly state in their policies what type of drug testing they'll be undertaking, why they are doing it, who they will be testing, how it will be tested, and what the limits are. An employer has some discretion as to what level THC is going to be acceptable.”

If employers don't have a policy in place to deal with this, he says, “then if they were to terminate someone's employment, it's likely to be found that they haven't acted as a fair and reasonable employer.”