Minister of Justice and Constitutional Development and Others v Prince (CCT108/17)  ZACC 30 (18 September 2018)
The prohibition of the personal use or cultivation of cannabis by an adult in private for his or her personal consumption in private is inconsistent with the right to privacy entrenched in the Constitution and is constitutionally invalid.
In 2017, in the case of Prince v Minister of Justice  ZAWCHC 30; 2017 (4) SA 299 (WCC), the High Court held that both sections 4 and 5 of the Drugs and Drug Trafficking Act 140 of 1992 (Drugs Act) needed to be amended to ensure that they did not apply to persons "who use small quantities of cannabis for personal consumption in the privacy of a home, as the present position unjustifiably limits the right to privacy". The High Court stated that it is Parliament that should determine the extent of what would constitute small quantities in private dwellings. The High Court suspended the order of invalidity for a period of 24 months from 31 March 2017.
Because the High Court found that parts of the Drugs Act were unconstitutional, the matter was referred to the Constitutional Court to consider an order of constitutional invalidity. The Constitutional Court has now decriminalised the possession and cultivation of cannabis in private by adults for personal private consumption. The Court relied on the right to privacy to reach this result. Although the order was suspended until Parliament can fix the defects in the current law, the Court provided interim relief that will make it unlawful for the police to arrest adults who privately cultivate, possess or use relatively small amounts of cannabis. The effect of this is that an adult person may use or be in possession of cannabis in private for his or her personal consumption in private.
This ruling does not extend to the use, including smoking, of cannabis in public or in the presence of children or in the presence of non-consenting adult persons. The ruling also does not extend to the cultivation or possession of cannabis with the intention of selling it. This means that it is still a criminal offence to grow dagga commercially or to deal in dagga.
We do not think this judgment, which decriminalises the possession and cultivation of cannabis in private by adults for personal private consumption, directly affects employer's policies regarding drugs at the workplace. Just as an employee can drink in the privacy of her/his home (which is also not a criminal offence) and still be disciplined if they arrive at work under the influence of alcohol, so too will workplace prohibition on drug use still apply. The General Safety Regulations made in terms of the Occupational Health and Safety Act (OHSA) state that an employer may not permit any person who is or who appears to be under the influence of intoxicating liquor or drugs to enter or remain at the workplace.
Extract from the judgment:
Do the impugned provisions limit the right to privacy?
 It seems to me that, with changes dictated by the context, what Didcott J said in the excerpt quoted earlier from Case as qualified by Langa J in the same case applies with equal force to the case of the possession, cultivation and use of cannabis by an adult in private for his or her personal consumption in private and in the absence of children. What this means is that the right to privacy entitles an adult person to use or cultivate or possess cannabis in private for his or her personal consumption. Therefore, to the extent that the impugned provisions criminalise such cultivation, possession or use of cannabis, they limit the right to privacy. The High Court pointed out that the State did not plead that the impugned provisions did not limit the right to privacy. During the hearing, I did not understand counsel for the State to argue that the impugned provisions did not limit the right to privacy. However, even if that was the State's case, not much was said in support of such a contention. In my view, the High Court correctly concluded that the impugned provisions limited the right to privacy.
 I am of the view that the prohibition of the performance of any activity in connection with the cultivation of cannabis by an adult in private for his or her personal consumption in private is inconsistent with the right to privacy entrenched in the Constitution and is constitutionally invalid. The reasons for this conclusion are the same as those given in this judgment as to why the prohibition of the use or possession of cannabis by an adult in private for his or her personal consumption in private is inconsistent with the right to privacy and, therefore, invalid. Therefore, to that extent, section 5(b) read with the definition of the phrase "deal in" in section 1 of the Drugs Act is constitutionally invalid.
 It seems to me that, indeed, there was no persuasive reason why the High Court confined its declaration of invalidity to the use or possession or cultivation of cannabis at a home or in a private dwelling. In my view, as long as the use or possession of cannabis is in private and not in public and the use or possession of cannabis is for the personal consumption of an adult, it is protected. Therefore, provided the use or possession of cannabis is by an adult person in private for his or her personal consumption, it is protected by the right to privacy entrenched in section 14 of our Constitution.
 The effect of the above reading-in is the following:
- an adult person may, use or be in possession of cannabis in private for his or her personal consumption in private.
- the use, including smoking, of cannabis in public or in the presence of children or in the presence of non-consenting adult persons is not permitted.
- the use or possession of cannabis in private other than by an adult for his or her personal consumption is not permitted.
- The cultivation of cannabis by an adult in a private place for his or her personal consumption in private is no longer a criminal offence.
 The above reading-in means that, if a police officer finds a person in possession of cannabis, he or she may only arrest the person if, having regard to all the relevant circumstances, including the quantity of cannabis found in that person's possession, it can be said that there is a reasonable suspicion that a person has committed an offence under section 40(1)(b) or (h) of the Criminal Procedure Act. I think that the references to possession of cannabis, "for personal use," or "for personal consumption" help to ensure that we do not have to specify the amount or quantity of cannabis that may be possessed. We only need to say that the amount that may be possessed is an amount for personal consumption.