By Lizle Louw and Shane Johnson, Employment Law Specialists at Webber Wentzel

After the cannabis judgment* handed down by the Constitutional Court in 2018, it is now widely known that adults may use, possess and cultivate cannabis privately in South Africa.

The judgment raises critical questions around medical testing in the workplace, especially at mines, where employees have to operate complex machinery and may endanger their own lives and those of others if their faculties are impaired. Employers in the mining industry are obliged to maintain a safe working environment and may exclude employees under the influence of an intoxicating substance (which includes cannabis) from entering the workplace or remaining at work.

Impairment caused by cannabis

In general, when cannabis is smoked, the following occurs:

• Impairment will start immediately and last for between 6-8 hours.
• Duration of impairment may last longer if there are higher levels of tetrahydrocannabinol (THC) in the cannabis used.
• Other factors (lack of sleep, use of other medication, consumption of alcohol and other medical conditions) can increase the duration and level of impairment.

When cannabis is consumed in other ways (e.g. ingesting through oils), its effect on the human body can differ, especially where certain cannabinoids are removed.

Cannabis can negatively impact on an employee's occupational capacity in many ways, including -

• performing tasks slower;
• performing poorly when handling routine, monotonous tasks;
• difficulty in multi-tasking;
• difficulty in taking instructions;
• difficulty in making crucial decisions (especially in high-risk situations);
• difficulty in operating machinery and/or motor vehicles.

Practical difficulties with cannabis testing at mines

Traces of cannabis can be found in the human body for up to six months after use, so it is challenging to determine the extent of impairment (if any) after such a long time.  The purpose of the testing for cannabis is to prevent employees who are under the influence of an intoxicating substance to enter the workplace to prevent safety risks.  If employees test positive for cannabis, they are not necessarily still influenced by it and may not present a safety risk.

If mining companies simply apply the zero tolerance policy (as with alcohol) to cannabis testing, employees may argue that they acted within the constraints of the cannabis judgment, they are not "under the influence" of cannabis (and therefore not a safety risk) and that they are treated unfairly in not being allowed to work and/or losing remuneration for that specific shift.

Difficulties may also arise when employees consume cannabis for medical reasons.  Will the employer's health and safety obligations trump a possible discrimination claim by the employee who elects to use cannabis for medical treatment?

Some employees of mines do not work in hazardous environments and work strictly in an office environment.  Consideration should be given whether the same stringent policy and testing mechanisms should be applied in non-hazardous areas.

Policy considerations

Employers in the mining industry should reconsider their current substance abuse policies.  The following questions should be considered:

• Is a zero tolerance policy on cannabis justified given the workplace/s?
• How is it possible to test if employees are "under the influence" of cannabis and therefore constitute a safety risk as opposed to just having traces of cannabis in their bodies?
• Should the policy be different for non-hazardous working areas?

In light of the cannabis judgment, it is necessary for cannabis to be regulated in its own section of companies’ substance abuse policies. The policy should also include a testing procedure and the circumstances under which testing will occur.

It may also be useful for to run an employee training programme on testing for cannabis. This will ensure that all employees are aware of the substance abuse policy and cannabis testing procedure.

* Minister of Justice and Constitutional Development and Others v Prince; National Director of Public Prosecutions and Others v Rubin; National Director of Public Prosecutions and Others v Acton and Others [2018] ZACC 30