Criminologist Professor Alex Stevens has refuted media reports that reducing penalties for cannabis possession has led to increased drug use, crime and health problems. He said published data shows that these claims are unfounded and in fact highlight that cannabis use and crime have gone down since the 2004 declassification of cannabis to a class C substance.
He said: ‘Government policy on cannabis hit the headlines again recently, when both the Daily Mail and the Daily Telegraph ran articles on it claiming reductions in penalties for users of the drug have increased both crime and drug-related hospital admissions. If cannabis declassification did cause these effects, it would be an interesting and novel finding. Most researchers who have studied this issue have found little evidence of changes in use or related harms as a result of changes to penalties for users.
‘There are two national surveys that provide information about trends in cannabis use. The British Crime Survey (BCS) includes people aged 16 to 59. The Survey of Smoking, Drinking and Drug Use among Young People in England includes school pupils aged 11 to 15. Eleven per cent of 16 to 59 year-olds reported that they had used cannabis in the year before cannabis was moved down to class C in 2004. This figure was 13 per cent among 11 to 15 year-olds. By 2009, this figure had fallen to eight per cent in the older age group, and to nine per cent in the younger. It is very hard to square these reductions with a claim that the changes in 2004 caused cannabis use to rise. Over the same period, crime (as estimated by the BCS) fell by 17 per cent.
‘So what is the source of the claims that appeared in the Mail and the Telegraph? They are based on two papers presented to the Royal Economic Society, which remain unpublished. One of them uses rates of admission to hospital that were recorded as having been related to ‘harder’, Class A drugs. It links these rates to the period in 2001 to 2002 when the cannabis warning scheme was introduced in Lambeth, but nowhere else. It is reported to show that this caused a durable increase in hospital admissions amongst men of between 40 to 100 per cent.
‘This is quite a claim. To make us confident that it is accurate, the researchers would need to do several things. They would need to show that cannabis use actually rose, which they appear not to have done. They would then need to establish a causal link from cannabis use to hospital admissions for harder drugs. This would be possible if there were clear evidence of a ‘gateway effect’ that makes cannabis users move on to more dangerous substances. The problem is that, despite decades of searching, such clear evidence is still missing.
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