Contrary to what you might expect, Levine and Small found that people arrested for marijuana possession in New York generally are not smoking pot in public. "Before being approached by the police," they note, "most people arrested for misdemeanor marijuana possession were actually not guilty of what they were charged with."

Why do police waste time and resources manufacturing crimes? Levine and Small note that busting pot smokers is a relatively safe and easy way to pad arrest figures, which creates the illusion of productivity, and generate overtime pay, a practice known as "collars for dollars."

From the collars' perspective, getting arrested for a trivial, victimless offense, which saddles them with criminal records that can impair their ability to obtain an education and make a living, is humiliating and embittering. It is especially rankling because police seem to be targeting poor black and Hispanic men for treatment that would never be tolerated if it were aimed at affluent white New Yorkers.

Survey data indicate that among 18-to-25-year-olds, the age group where the pot busts are concentrated, whites are more likely than blacks or Hispanics to smoke marijuana. Yet Levine and Small found that in New York, blacks and Hispanics are, respectively, five and three times as likely to be arrested for marijuana possession.

For pot smokers caught in the NYPD's dragnet, is Bloomberg's position on marijuana -- "I enjoyed it; you'd better not" -- hard to accept? You bet it is.