There are Several Reasons why the drug phenomenon has proved to be a difficult analytical puzzle for social scientists. One is that the field of study itself shifts depending upon the interest of the analyst, ranging from topics as diverse as drug abuse, the political and judicial impact of violence and corruption engendered by the illegality of drug trafficking, and the nature of the groups that generate revenue from drug trafficking—and the purposes to which they put that money. Another reason, of course, is the fact that hard data are often absent; measurement problems are severe. A third reason, compounding the second, is that generalizations decay quickly in this area, as zones of production, patterns of consumption, trans-shipment points, and methods and relationships among trafficking groups, state agents and local producers can all change quickly.