The legalisation of cannabis by the High Court of South Africa, which was confirmed by the Constitutional Court, imposes challenges to
occupational medical practitioners acting as medical review officers in compliance testing and fit-for-service medical examinations. The
lipophilic character of the psychoactive component of cannabis, delta-9-tetrahydrocannabinol (Δ9-THC), and its prolonged elimination
half-life, create challenges for the ethically and scientifically correct management of the legal use of cannabis in risk-sensitive environments.
Important issues to consider in testing for cannabis use are: the stance of ‘zero tolerance’; screening and confirmation cut-off concentrations;
and the bio-matrices used for testing. Constitutional rights relate to privacy, freedom, autonomy, freedom of religion and the equal
enjoyment of rights and privileges, which must be balanced against the health and safety of others.