The FBI's latest figures for drug arrests, noted by Mike Riggs earlier this afternoon, indicate that marijuana busts fell significantly between 2010 and 2011, from about 854,000 to about 750,000. That's a drop of 12 percent, compared to declines of 3 percent from 2008 to 2009 and 0.5 percent from 2009 to 2010. Marijuana arrests had been rising more or less steadily since the early 1990s, from about 342,000 in 1992 to a peak of 873,000 in 2007. During that period this is the first time there have been three successive years in which total pot busts fell, and last year's decrease is the biggest single drop since 1992. In 2011 marijuana accounted for half of all drug arrests, which have been falling since 2006; last year's total, 1.5 million, was about the same as in 2002 and more than twice the number in 1980.

Have tight budgets encouraged a refocusing of police resources? Are the priorities of state and local law enforcement agencies (which are responsible for 99 percent of marijuana arrests) finally reflecting growing public tolerance of cannabis? Maybe. Let's check back around this time next year.

[I have reformatted the chart so you can see the trend more clearly.]