Why Cannabis Laws Should Treat 25 as the Real Age of Majority
A 25-Year Threshold: A Libertarian Case for Protecting Tomorrow’s Liberty
Written by: Charl Heydenrych
The Department of Justice and Constitutional Development recently released the draft regulations for the Cannabis for Private Purposes Act, inviting public comment until March 5, 2026. While the draft provides clarity on possession limits, proposing 600g to 1.2kg for adults, it sticks to the traditional legal threshold of 18 years.
As we codify our post-prohibition landscape, we must confront a difficult scientific and philosophical question: If the goal of the law is to protect individual agency, is 18 actually the right age?
The Protective Precedent: Guarding the Developing Mind
Society has long recognized that certain “adult” activities require a level of maturity that the young do not yet possess. We already maintain strict legal barriers to protect minors from the weight of the adult world, specifically regarding pornography, extreme violence, and alcohol. These laws exist because we acknowledge that exposure to high-intensity stimuli or addictive substances can distort a developing psyche.
If we accept that a 17-year-old requires legal protection from the psychological impact of pornography or the physiological toll of alcohol, we must apply that same logic to the neurological impact of high-potency THC. To do otherwise is to ignore the unique risks cannabis poses to the biological seat of reason.
The Schizophrenia Link: What the Science Says
Peer-reviewed research indicates that the “adult” brain is not actually mature at 18. The prefrontal cortex (the seat of executive function and decision-making) continues to undergo significant “synaptic pruning” until approximately age 25.
More alarmingly, the link between early cannabis use and schizophrenia is no longer mere “reefer madness” propaganda. Longitudinal studies show that high-potency THC use in a developing brain can trigger a “dopamine storm,” potentially leading to permanent psychotic disorders in those with a genetic predisposition. If a substance has the potential to permanently damage the organ required for rational thought, can its use by a 19-year-old truly be considered an “informed” choice?
The Libertarian Paradox: Current Self vs. Future Self
This creates a profound philosophical conflict: whose rights should be protected? On one hand, we must respect the immediate autonomy of the individual to make private lifestyle choices without state interference. On the other hand, we have the rights of that same individual as their future self.
Libertarianism is rooted in the Non-Aggression Principle (NAP) and self-ownership. At first glance, an age limit above 18 seems like paternalism. However, many modern libertarian scholars argue that you cannot sell yourself into permanent slavery because you cannot alienate your own will. Liberty is the protection of your capacity to make choices tomorrow. If a young person uses a substance that induces a permanent state of schizophrenia, they have, in a biological sense, surrendered their rational mind. Without the mind, the “self” cannot be owned. In this view, the state’s role is not to dictate lifestyle, but to act as a temporary steward of an individual’s future autonomy until they are biologically capable of guarding it themselves.
Beyond Legislation: The Education Mandate
However, state involvement in private choices is a blunt instrument that many find inherently distasteful. If we are to argue that the law should restrict access to those under 25, we must also acknowledge that legislation alone is an insufficient and perhaps secondary solution.
If the goal is to protect the individual’s future self without relying solely on the heavy hand of the state, much more effort should be put into the education of the community. True liberty requires an informed populace. A restriction on the books is a hollow defence if the community does not understand the underlying neurological stakes. Robust, science-based education initiatives must empower families and individuals to make these choices voluntarily, potentially reducing the need for state intervention over time.
A Case for Age 25
A reasoned argument for an age limit of 25 in the meantime does not abandon libertarian values; it refines them based on two pillars:
Informed Consent Requires Mature Faculty: For consent to be valid, the individual must have the biological capacity to weigh long-term consequences. If the brain’s “braking system” isn’t fully wired until 25, the “consent” given at 19 is neurologically incomplete.
Protection of Future Autonomy: By restricting access to neuro-disruptive substances until the brain is fully formed, the age restrictive law seeks to preserve the individual’s future capacity to exercise their rights.
Conclusion
The South African government’s current draft is a step forward for privacy and individual rights, but a leap in the dark regarding public mental health. If we treat 18 as the finish line for maturity, we ignore a biological reality. Whether through a refined legal threshold or a massive shift toward community education, we must prioritize the protection of the most important property any human owns: their mind.
Charl Heydenrych is a retired human resources practitioner and a libertarian.
An interesting argument ... Ukraine itself if I am not mistaken conscripts from 25 onwards, a remarkable policy given that most nations conscripted from 18 onwards. (Conscription however at any age is the utilitarian crime against Humanity that led to the slaughterhouse of WW1, the implosion of the West). You pose a crucial challenge, namely when does Trevor Watkins' Harm Consent Rule, the HCR, apply if psycho/biologically the human brain is a work in progress until 25? It also poses a similar challenge to the "Nature of Us", the NoU, a statistical modelling of who we are as a more comprehensive alternative to Ayn Rand's "Nature of Man", the NoM, as the appropriate source of ethics and morality for us. In your argument the fulfillment of the brain development would be just another attribute of the NoU. Why this matters is that the HCR coupled to the NoU is the Non Aggression Principle, the NAP, at its highest possible resolution so far. That which constitutes the initiation of physical force against others without consent (aka violence) can be precisely determined via the HCR coupled to the NoU. The NoU can simply absorb the statistically validated age of maturity as yet another attribute of itself so that violations of HCR coupled to the NoU can be even more precisely determined. (For the NoU see: https://thetaooffreedom.substack.com/p/the-nature-of-us-nou?utm_source=publication-search)