Police efforts to fight drug gangs tend to lead to more violence and an increase in murders, according to a new international study. The authors, writing in the International Journal of Drug Policy, admit they were surprised by their own findings. Their hypothesis was that the results "would demonstrate an association between increased drug law enforcement expenditures or intensity and reduced levels of violence". But that's not what they showed. Instead, they report: "From an evidence-based public policy perspective and based on several decades of available data, the existing scientific evidence suggests drug law enforcement contributes to gun violence and high homicide rates and that increasingly sophisticated methods of disrupting organisations involved in drug distribution could paradoxically increase violence."