"To provide a sense of the intensity of enforcement, we calculated the risk a marijuana user faces of being arrested for possession. If calculated per joint consumed, the figure nationally is trivial—perhaps one arrest for every 11,000–12,000 joints.4 However, the relevant risk may be the probability of being arrested during a year of normal consumption. Since marijuana is mostly consumed by individuals who use it at least once a month,5 we estimated the risk that such individuals face. We know from prior studies (e.g., Reuter, Hirschfield, and Davies, 2001) that these risks are higher for youth. Table 2.2 presents separate estimates for those aged 12–17 and for the entire population 12 and over. We observe that the annual risk of misdemeanor arrest for those 12–17 (6.6 percent) is more than twice the rate for the full population (3.0 percent)."

Source

Kilmer, Beau; Caulkins, Jonathan P.; Pacula, Rosalie Liccardo; MacCoun, Robert J.; Reuter, Peter H., "Altered State? Assessing How Marijuana Legalization in California Could Influence Marijuana Consumption and Public Budgets" Drug Policy Research Center (Santa Monica, CA: RAND Corporation, 2010), p. 8.
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