Substance abuse in the workplace, particularly in some industries such as the BPO/call centre industry, can have significant impacts. It is acknowledged that substance abuse can lead to absenteeism, accidents, illness, and increased mortality, which in turn can increase employer costs.

In South Africa, the Prince Judgment by the Constitutional Court has indeed affirmed the right to use, cultivate, and possess cannabis in private, which has led to the drafting of the Cannabis for Private Purposes Bill. This bill, once enacted, will allow individuals to possess up to 100g of dried cannabis. However, the intersection of private rights and workplace regulations is complex, especially when considering the Occupational Health and Safety Act (OHSA) and the need to maintain a safe work environment.

Regarding labour court cases involving cannabis at the workplace, there have been several notable rulings including:

1. Marasi v Petroleum Oil and Gas Corporation of South Africa - The Labour Court confirmed that employers are entitled to set workplace policies regarding substance abuse, including the use of cannabis, to maintain health and safety in the workplace.

2. Labour Court ruling on PFG Building Glass employees: The court ruled that the decriminalization of cannabis for private use does not extend to the workplace, and employers have the right to enforce zero-tolerance policies outlawing the use of cannabis.

The legal principles summarized from these cases indicate that:

- The Constitutional Court's decriminalization of private cannabis use does not protect employees from disciplinary action if they contravene company policies.

- Employers can enforce policies that align with health and safety legislation, including zero-tolerance for substance use in the workplace.

Lessons for employers include:

- Clearly communicate workplace policies regarding substance use, including cannabis.

- Ensure that policies are in line with current legislation and health and safety requirements.

- Provide training and support for employees to understand the implications of these policies.

- Consider the legal and safety implications when drafting and enforcing substance abuse policies.