One last call for the legalisation of cannabis

Although considered acceptable on an individual basis by many, little has changed to the cannabis laws across most of Europe over the last few years. Not, actually, since its reclassification in Britain from Class C to Class B drug in May 2008[1], moving it up the scale away from ‘soft drugs’ like anabolic steroids, and towards the ‘harder drugs’ of the Class A crack and cocaine, amongst others.[2] In the aftermath of this change in policy, Professor David Nutt was sacked from his position as head of the Advisory Council on the Misuse of Drugs (the UK government’s official advisory body) for outing criticism against the decision in light of scientific evidence.[3] It is my belief that this is just one example of politicians refusing to reflect upon the state of cannabis legality from a neutral standpoint, and I will now attempt to bring some transparency into the picture.

To do so, I will make an immediate distinction in the arguments surrounding this debate; using medical evidence on the one side and considerations of a more philosophical nature on the other. Although the two sides are inextricably linked, this separation allows for greater clarity as to where the differences in opinion lie, and where, I will argue, there needs to be a re-evaluation of these differences in the interest of policy consistency.

Beginning with the medical arguments, it is necessary to state that cannabis can indeed be harmful. Denying this claim is dangerous and, if we are to trust any of the scientific research into the issue, quite clearly wrong. There can be a lot of differentiation in the harm caused, however, depending on which indicators are being measured. For example, by analysing data from the often cited Dunedin longitudinal study[4] – following 1,037 individuals from birth and so far gathering more than 40 years of evidence – Madeline Meier and her team at Duke University in Durham, North Carolina, published a study observing the effect of cannabis use on an individual’s IQ score.[5] The results show that ‘the heaviest and most persistent adolescent-onset users [of cannabis] had experienced an average decline of eight IQ points from childhood to adulthood.’ Furthermore, there was a clear decrease in adverse effects as the severity of use mitigated.[6] In comparison, ‘adult-onset cannabis users did not appear to experience IQ decline as a function of persistent cannabis use’, and non-users had an average increase of one IQ point.[7]

Another study by Professor Nutt et al. used 16 harm criteria (such as drug-specific mortality, injury and family adversities etc.)[8] to measure the harm to both ‘users’ and ’others’ – collectively the overall harm.[9] These varying indicators were assigned to either the user or others, and within these two groups again split into categories of physical, psychological or social harm. In all, 20 drugs, both legal and illegal, were analysed and compared by merit of a multi-criteria decision analysis (MCDA), with levels of harm then weighted on a complex ratio scale and finally given an overall score out of 100 (‘with 100 assigned to the most harmful drug on a specific criterion [and] zero indicated no harm.’)[10]

The results show a significant harm caused by cannabis to both users and others, and are as follows:



Yet the argument against the legalisation of cannabis, from a stance of relative harm caused, is not as simple as it might now appear, for there are certain considerations from a medical perspective that actually support the opposite. Madeline Meier et al.’s study, for example, shows a significant loss in cognitive ability for heavy cannabis consumers – but only for adolescent-onset users. It follows that a legalisation of cannabis, thus a regulation of the market, could in reality serve as a precautionary mechanism and thereby be harm-preventive. This would result from the newly-found governmental ability to prohibit the purchase of cannabis by under-18s (or even under-21s given scientific evidence) as is currently the case with alcohol and tobacco. And more importantly: as is currently not the case with cannabis and other illegal drugs, for it is unlikely that illegal dealers are asking for proof of age.

By legalising and thereby regulating the cannabis market, two further effects would be seen: firstly, the cannabis consumed could be both cleaner and less potent; the Δ9-Tetrahydrocannabinol (Δ9-THC) content could be easily limited and the ratio to its antagonist Cannabidiol (CBD) decreased. Δ9-THC is the principal psychoactive chemical in cannabis, thus largely to blame for the symptoms often associated with consumption: anxiety, paranoia, memory lapses and even a trigger for a relapse of mental disorders such as schizophrenia, amongst others.[11] Conversely, CBD has been linked to a series of positive effects by recent studies: alleviating certain effects also caused by Δ9-THC thus working psychologically-protective; as well as a potential relief of symptoms from Multiple Sclerosis and use as an alternative therapeutic agent in the treatment of cancer, to name just a few.[12] [13] [14] And secondly, cannabis users’ access to other, harder drugs such as cocaine, which as we saw in Professor Nutt et al.’s study are far more harmful to both the user and others, would be prevented. For these drugs would not be on sale side by side with cannabis, as is currently more often than not the case.

We are left, then, without a clear answer. In light of the harm caused some might demand even tighter restrictions and consequent punishments for cannabis use, whilst others may well accept that it cannot be hindered and accordingly see its legalisation as the right step towards harm prevention. In this sense let us move onto the philosophical arguments, where we must begin by asking ourselves the following question: ‘to what extent may the government restrict our freedoms with respect to potential harms?’ Again splitting these harms into ‘others’ and ‘users’, we seem to accept that the former is entailed in this jurisdiction – it is under this principle that violence and theft are illegal. But what about the latter; what about the harms we potentially cause to ourselves? Here we touch on one of the traditional arguments by many liberalists, fed-up with the state imposing on their lives in situations where they feel it has no right to do so. After all, the nature of being an autonomous individual requires us to take responsibility. Thus it should be up to each of us, they argue, to evaluate both the benefits and costs of cannabis use and thus come to a personal decision, as is the case in many other outlets associated with a risk of harm – skiing, sky-diving, horse-riding and the like.[15]

And what about the financial aspects of cannabis’ legalisation? It is unfortunate that this debate may come down to a decision based on money, yet there are strong indicators that this could be the case. For example, since cannabis’ full legalisation in January 2014 in Colorado, the local government has seen a substantial increase in tax income: in January alone, sales of cannabis for recreational and medical purposes in that state exceeded $3.5 million – if this trend continues that would equate to, annually, approximately $40 million.[16] In addition to this, prior law enforcement costs could be saved. This money would then be freely accessible by the state to invest elsewhere in perhaps more pressing issues – for some maybe a sufficient argument on its own.

So where does this leave us? As I have now discussed, there are valid arguments for both the pro- and con- legalisation camps. Yet although there may well be no right answer as such, a responsible government has to accept, above all, that their policies must reflect consistency; that the basis of decision-making by which our societies are run hinges upon the same set of principles at all times, and is not merely a pick and mix of rules and conventions wherever it sees fit. So if the argument is made, for example, that cannabis is too harmful for it to be legal, and that the state must protect us all from these dangers, then this is a completely valid line to follow – as is the claim that all drugs that cause harm above a certain threshold should be illegal. For both of these claims we would thus require the policy to reflect scientific research into harm caused and, consequently, be implemented in a consistent fashion with respect to these findings. Yet this is not the case today. As we saw in the study of Professor Nutt et al., the drug that causes the biggest amount of harm to others by far – alcohol – remains legal, whilst LSD and mushrooms, which were found to cause no or almost no harm to others whatsoever, remain illegal. And nor is there any consistency in the total amount of harm caused by a drug and its status of legality, where again alcohol but also tobacco – another staple consumer good in our society – rank above cannabis yet remain legal.

For that reason, the first question we must all really ask ourselves is this: shall we keep cannabis illegal, and ban alcohol and tobacco too; or shall we keep alcohol and tobacco legal, and legalise cannabis too? Anything else would be nothing short of hypocrisy.

I wonder which option will be favoured.






[4] ‘The Dunedin Multidisciplinary Health & Development Study’ –

[5] Madeline H. Meier et al., 2012: ‘Persistent cannabis users show neuropsychological decline from childhood to midlife’ –

[6] ‘Drop in IQ linked to heavy teenage cannabis use’ –

[7] Madeline H. Meier et al., 2012: ‘Persistent cannabis users show neuropsychological decline from childhood to midlife’

[8] Full list of harm criterions: Drug-specific mortality, Drug-related mortality, Drug-specific damage, Drug-related damage, Dependence, Drug-specific impairment of mental functioning, Drug-related impairment of mental functioning, Loss of tangibles, Loss of relationships, Injury, Crime, Environmental damage, Family adversities, International damage, Economic cost, Community

[9] ‘Drug harms in the UK: a multicriteria decision analysis’, Prof David J Nutt, Leslie A King and Lawrence D Phillips [on behalf of the Independent Scientific Committee on Drugs]; The Lancet, Volume 376, Issue 9752, Pages 1558 – 1565, 6 November 2010

[10] ‘Drug harms in the UK: a multicriteria decision analysis’, Prof David J Nutt, Leslie A King and Lawrence D Phillips


[12] ‘Biology of Marijuana’, by Emmanuel S. Onaivi for Taylor & Francis publisher, 2002


[14] ‘Cannabidiol as potential anticancer drug’, by Paola Massi, Marta Solinas, Valentina Cinquina & Daniela Parolaro, April 2012