Steve Connor: Arbitrary classification has little to do with science

Analysis

The current system of placing illegal drugs into one of three classes – A, B or C – depending on their legal status, has long been criticised by medical authorities concerned that it is based on arbitrary considerations rather than evidence-based science.

Class A includes the highly addictive drugs heroin and cocaine, but it also includes ecstasy and LSD which many experts believe are far less harmful. Indeed, a study published in The Lancet in March 2007 found that alcohol and tobacco are more dangerous than cannabis, LSD and ecstasy, based on a range of measures such as physical harm to the user, the level of induced dependency and the wider effect of the drug on families and society as a whole.

The study, led by Professor David Nutt, then at Bristol University, and Professor Colin Blakemore, former chief executive of the Medical Research Council, developed a new system of ranking drugs according to their effects on users and those around them.

They studied 20 drugs in total, including legal as well as illegal substances, and two independent panels of experts ranked them according to harm. Heroin and cocaine came out first and second respectively, but alcohol was fifth and tobacco came ninth, ahead of cannabis (11th), LSD (14th) and ecstasy (18th).

All drugs were marked on the physical harm caused to the user, their tendency to cause dependence and their social harm – such as crime and NHS costs. Each was given an overall harm score by two groups of experts.

The message was clear: the scientific evidence places certain legal drugs, namely alcohol and tobacco, ahead of many illegal drugs in terms of harm to users and society at large.