The precautionary principle is frequently invoked in relation to drugs laws. The argument goes like this: if we are unsure of the risks of harms of a drug then it is safer to ban it as a precaution rather than wait until harms become apparent. As a principle, it is based on the supposition that since there are assumed to be no benefits of “illegal” drugs then banning them will have no downside or ‘disbenefits’ with the anticipated result that the banning of them will be beneficial to society and to users. 

At face value, the precautionary principle seems reasonable but, as I argued in the Eve Saville lecture at the Centre for Crime and Justice Studies last year, it is fraught with hidden harms and injustices especially if applied in an unthinking and arbitrary manner.

Here are eight examples where the precautionary principle with drugs falls down:

1. Increases personal harms
The penalties enforced in the banning legislation may cause more harm than the drug itself: a criminal record or even imprisonment for cannabis possession will almost certainly be more damaging to the individual and society than the drug itself. Criminalising users to deter them and others is the central plank of the current legislation that makes cannabis a Class B drug and the explicit reason why it was regraded up to Class B last year. This damages users who are caught in possession as it limits their career opportunities and is particularly hurtful to those using for medicinal reasons. It also costs the public purse large amounts through police and court time and prison costs – which was one reason why cannabis was downgraded to Class C in the first place!

2. Distorts markets to greater harm to society
When precaution results in a variety of different drugs being made illegal then markets and competition between them develop. There are incentives for drug dealers to sell the most profitable, most addictive and least likely to be detected drugs. This pushes the market in the direction of drugs such as heroin and crack which use small volumes and have no odour and away from cannabis which is bulkier and smelly. The harms of the former are much greater than those of cannabis yet the penalties for possession and supply are similar [7-v-5 years and life-v- 14 years respectively].  There are examples of young people initiating illegal drug use with heroin rather than cannabis simply because cannabis is harder to get hold of and deaths have been the result.
3. Impossibility to refute
When the precautionary principle is used to deal with a concern for health effects of drugs, such concerns can never by fully allayed since any drug can be associated with harms of some sort if widely enough used. There is therefore always justification for maintaining precautions and keeping drugs illegal. This was the basis of the last government’s decision to keep ecstasy Class A even though the evidence of harm was clearly much less than with other Class A drugs such as heroin and crack. Although the immediate harms were not as severe as Class A drugs, the Home Secretary said that there were concerns about the long-term effects so it would consequently not be downgraded.  Not much consolation to the many people in prison for up to 5 years for possession of ecstasy for personal use – an unlikely and unknown long-term possible health consequence is given as justification for an immediate destruction of liberty and livelihood.

4. Disproportionate penalities
The precautionary principle also fails to take into account the proportionate risks from drugs and the absolute level of risk that should be required to ban a drug. I have argued that some metric of harm developed in reference to other harmful behaviours e.g. horse riding, rock climbing or sun-tanning should be invoked as a threshold of risk to decide if any drug should be made illegal. Some argue that as illegal drugs have no value then there are no dis-benefits of banning them. The flaw in this argument vis a vis criminalisation has been made in Point 1.

5. Entrenchment of a flawed institutionalised moral position on drugs
Precaution is often either overtly or subconsciously based on the argument there are no benefits to the use of the drug so that it should therefore be made illegal.  This argument reflects a biased and entrenched institutional position that the establishment and law makers alone understand costs and benefits and that drug users are all dependent, addicted losers. In fact, most people who use illegal drugs do so because they want to, NOT because they are addicted. For those for whom illegal drug use is a choice, benefits include relaxation, dancing, mind expansion etc;  these are real benefits/motivators that should not be ignored by legislators

6. Encourages other drug use
The most costly and perverse consequence of the precautionary principle is that it encourages the use of legal drugs which are more harmful than the ones being banned. It can be argued that the epidemic of alcohol-related health harms that the UK is experiencing now is partly driven by people who might use drugs that are safer than alcohol, such as cannabis and ecstasy, being deterred by the risks of criminalisation and/or misinformation about the relative harms of these drugs, so are driven to drinking instead. It is seriously questionable whether there is any health justification for criminalising the use of drugs that are safer than alcohol. Punishing drug users – but not drinkers or tobacco smokers – to protect them and society from health harms is ineffective, uneconomic, morally indefensible and patently unjust. The growing use of cannabis in retired people in the USA when they no longer have to fear workplace drug-testing reflects the true deterrent effects of the law to limit free choice.

7. Blocks new drug discovery
The precautionary principle also limits the development of new drugs that might be safer than alcohol – such as alcohol alternatives – which would be subject to a much higher level of safety than alcohol itself.

8. Denies innovation and medical progress
Some drugs, particularly LSD, MDMA and psilocybin, were showing promise as therapeutic agents before they were made illegal. This research then stopped as a consequence and only now, 40 years on is being resurrected with very promising findings. The recent banning of mephedrone means that new antidepressants and other treatments e.g. for obesity and narcolepsy that might have emerged from that chemical series will now not happen. It is not that such drugs would necessarily be illegal but the regulatory and legal complexities of working in this chemical arena and the possibility that new drugs might be outlawed if legislation changes in the future provides too big a disincentive to the pharmaceutical industry. 

Drugs present a variety of dangers to those that take them – however, using the precautionary principle as the basis for prohibition risks creating unnecessary harms without properly protecting users. If we are going to have a coherent and effective strategy to tackle the problems that drugs cause, removing the harms caused by the precautionary principle must be a priority.


The Tories’ actions in the run up to the election showed a worrying conviction that methadone is a short term solution to addiction. One option they appear to be considering is to encourage opioid addicts to seek “cure” rather than continued treatment, achieved by limiting the duration of methadone treatment, say to 6 weeks. This ambition would be both scientifically inaccurate and economically insane. It is based on a discredited view of addiction being a transient single event equivalent to moral lapse that can be cured – in medical terms the equivalent of a fractured bone or a chest infection.  All medical evidence in the past 40 years has supported the centuries old view of addicts themselves that is incorporated in the Alcoholics Anonymous axiom – once an addict always an addict.  This doesn’t mean that drug or alcohol use is inevitable, merely that the addiction reflects both a personal vulnerability and a learned behaviour so that once experienced there is no “resetting” back to normal: experience can’t be erased! The risk of relapse is always present and most people will experience more than one episode of drug misuse during their life.  Addiction is best conceptualised as a chronic recurring illness such as diabetes and asthma where life stresses and other factors predispose to relapse so ongoing prophylactic treatment is required. Longitudinal studies of many addictions show that the outcome for long-term treatment is similar to that for these other enduring illnesses.

Even if you deny the medical model of addiction, the economic evidence also strongly supports the value of maintenance methadone treatment with multiple studies over the past 50 years proves that enduring treatment with this heroin substitute leads to reduced deaths and other medical illnesses and less crime both acquisitive and violent. For every unit of investment in methadone, three are saved from these other sources. It seems likely that similar values obtain for other heroin maintenance treatments such as buprenorphine, and for treatments of other addictions e.g. varenicline in smokers, acamprosate and naltrexone for alcoholics. This does not mean that abstinence treatments should not be offered or that psychological interventions have no value, rather if these don’t work or are unacceptable to the addict then maintenance should be allowed.

It seems perverse that the UK government might be considering reverting to a primitive discredited moral model of addiction when the USA – previously the bastion of this approach – has recently appointed Tom McLelland to the role of deputy director of drug policy. Tom’s research played a major role in the medical model of addiction gaining acceptance and will play an increasingly important place in US policy.

The Conservatives see residential rehabilitation as the alternative to methadone. It certainly may be for a proportion of (although not all) addicts. However, the costs involved in residential rehabilitation are significantly higher than methadone treatment. Whether the Conservatives prove willing to fund such treatment, particularly in an era of austerity within the public sector, remains to be seen. Methadone treatment may yet survive, if only for reasons of financial expediency.

McLleland AT Lewis DC O’Brien CP, Kleber HD  (2000) Drug dependence, a chronic medical illness: implications for treatment, insurance, and outcome evaluations J American Medical Association 284,1689-1695 doi:10.1001/jama.284.13.1689

The debate about the costs of alcohol has been resurrected today by the NICE report ( that recommends that the price of alcohol should be regulated according the concentration of alcohol in the drink. Obvious you might think – why should there be differences in the pricing of the active drug component of different drinks – since the effects of the drug are simply and causally related to the dose taken?  Yet when the Scottish parliament attempted to bring in this as law last year, the Labour party blocked it on the grounds that it would penalise the poorest members of society. A truly bizarre idea that is wrong in both fact and in principle. The poor who are dependent on alcohol find this addiction eats up their income in the same way as the costs of tobacco used to until ten years ago when the original New Labour government put up the price and drove down use. What is never discussed is why alcohol use should not be price sensitive when tobacco use is, probably because it is well known that both are equally susceptible to cost controls.

Today we have a repetition of this intellectual dishonesty but this time from the drinks industry. In response to the NICE report we heard the usual mealy-mouthed protestations that there is no evidence that unit pricing reduces intake.  This statement is technically correct since it’s never been explicitly tried but already alcohol is priced through taxation according to strength. Beers are priced lower than wine which in turn is cheaper than spirits, and people do tend to drink lesser volumes of the more expensive formulation. Moreover the “lack of evidence” claim is an attempted distraction as there is overwhelming proof from many countries over many centuries that increasing the price of alcohol lessens intake.

On top of this we get the claim that alcohol dependent people would not be deterred by price increases so the policy wouldn’t work anyway. Personal anecdotes of dependent drinkers who claim that price wouldn’t deter them are wheeled to support the industry position. What is conveniently overlooked is that most drinkers are not dependent and so are price sensitive and this particularly applies to the young and novice drinkers. The rise of youth drinking is directly related to the reduction of the real price of alcohol that has occurred over the past twenty years. Increasing the cost of alcohol will therefore reduce the rising wave of binge drinking in the young with its accompanying toll of deaths, disability and enduring medical complications. It will also have a minor, but likely significant, effect to reduce drinking in the older age groups which are increasingly experiencing alcohol-related heart and liver disease.

There can be no moral argument for some forms of alcohol, such as 8% cider,  to cost less than a fifth of the same amount of alcohol in wine or spirits when the intoxicating value is the same. The health effects are these ciders are therefore 5x more damaging than those of comparable strength drinks which is why they make a major impact on our health care costs.  Alcohol related damage in the UK runs to tens of billions of pounds a year so each middle class wine drinking tax payer is paying thousands of pounds in taxation to cover this. Most would surely agree that a small hike in the costs of alcohol that significantly reduced overall alcohol consumption and health damage would make economic sense.