THE drugs watchdog of the United Nations has rebuked the UK government's policy change on cannabis, saying it sent a confusing message to young people. UN experts also warned that a major increase in the potency of cannabis means it now poses health risks similar to those of heroin. The decision to reclassify cannabis as a Class C drug - made by the Home Secretary in 2004 - was implicitly criticised by Antonio Maria Costa, the executive director of the UN Office on Drugs and Crime, who warned of the growth in its use. Cannabis had become more potent in...