“THE breakfast of champions”, Keith Richards of the Rolling Stones once said, of cocaine and heroin speedballs. The government disagreed, and in 1971 passed the Misuse of Drugs Act. Mr Richards’ breakfast ingredients were labelled class A; classes B and C were for milder fare. Police are supposed to treat users of class A drugs the harshest: “a prosecution is usual” for those caught in possession, say Crown Prosecution Service guidelines, whereas those found with class Bs and Cs must usually possess more than a “minimal quantity” to be taken to court. In recent years the opposite seems to have been happening. According to an analysis of Ministry of Justice data by Release, a drugs charity, police are more likely to prosecute those they arrest with class B and C drugs, and let those arrested with class As off with a caution (see chart). Why are those arrested with what are notionally the mildest drugs the most likely to end up in court?

One reason, Release suggests, is that police may discriminate against people further down the social scale. The most commonly seized class B drug is cannabis, popular among students, the unemployed and the poor. Class A drugs such as cocaine, by contrast, have a following among bankers, journalists and politicians, whom officers may decide to wave on.

But most of those caught with cannabis are not arrested in the first place: 65% are let off with a warning or on-the-spot penalty, meaning they do not show up in Release’s figures. The minority who are arrested for cannabis possession may therefore have done something particularly worthy of prosecution. Research by the London School of Economics and Release suggests that police target stoners who persistently smoke in public places; repeat offenders are considered better candidates for a court appearance.

David Nutt, an academic and former government adviser, says police may treat some class A drugs as a medical rather than criminal matter. And officers may use their discretion to crack down on hard drugs that are misclassified as soft, and vice versa: it strikes most as odd that ecstasy (class A) is considered more dangerous than ketamine (class C), for instance. Either way, the upside-down prosecution figures are further evidence that the ABC system is showing its age.