The latest data from the government-sponsored Monitoring the Future Study, released today, indicate that marijuana use by teenagers, which fell from 2001 through 2006, may be on the rise again. Between 2008 and 2009, the share of students who reported smoking pot in the previous month rose from 5.8 percent to 6.5 percent among eighth-graders, from 13.8 percent to 15.9 percent among 10th-graders, and from 19.4 percent to 20.6 percent among 12th-graders. This is the third year in a row that self-reported marijuana use has risen among high school seniors, who are now more likely to smoke pot than cigarettes (PDF). According to the Associated Press, "researchers said" that "the increase of teens smoking pot is partly because the national debate over medical use of marijuana can make the drug's use seem safer to teenagers." Yet the first medical marijuana law, California's, was passed in 1996, and during the subsequent 13 years another dozen states adopted similar policies. If these laws are signaling teenagers that smoking pot is safe, why the lag? A June 2008 report from the Marijuana Policy Project noted (PDF):

More than a decade after the passage of the nation's first state medical marijuana law, California's Prop. 215, a considerable body of data shows that no state with a medical marijuana law has experienced an increase in youth marijuana use since their law's enactment. In fact, all states have reported overall decreases—exceeding 50% in some age groups—strongly suggesting that enactment of state medical marijuana laws does not increase teen marijuana use.

To put the recent upward trend in perspective, past-month marijuana use by high school seniors is still only about half as common as it was in 1979. Still, federal officials lament that "the percentage of eighth-graders who saw a 'great risk' in occasionally smoking marijuana fell from 50.5 percent in 2004 to 48.1 percent in 2008 and 44.8 percent this year." It speaks volumes about the scientific basis of our current drug policy that the people charged with implementing it openly pin their hopes for success on their ability to trick 13-year-olds into believing something that is patently false.