On Wednesday I noted, apropos of Attorney General Eric Holder's promise to "vigorously enforce" marijuana prohibition in California whether or not Proposition 19 passes, that the government has a long way to go on that score: It currently catches, at best, 3 percent of marijuana offenders each year (while the feds are responsible for less than 1 percent of those arrests, representing less than 0.03 of all offenders). These numbers are generous, since they assume that data based on self-reports in surveys do not understate the prevalence of marijuana consumption, which they probably do. In any case, it's clear that only a small percentage of people who violate the ban on marijuana are getting arrested, a situation that invites arbitrary enforcement. A report released today by the Drug Policy Alliance and the California NAACP illustrates that problem, finding that from 2006 to 2008 "police in 25 of California's major cities arrested blacks at four, five, six, seven, and even 12 times the rate of whites." The racial disparities are not explained by differences in drug use, since the government's survey data indicate that "young whites use marijuana at higher rates than young blacks."

The authors—Harry Levine, Jon Gettman, and Loren Siegel—found the most dramatic racial disparities in Torrance and Pasadena, but bigger cities such as San Diego and Los Angeles also arrested blacks for marijuana possession at far higher rates than whites (six and seven times as high, respectively). As in their report released last June, which broke down data on California marijuana arrests by county, Levine et al. do not ascribe these disparties to racism:

Why have police in California been arresting young blacks at higher rates than young whites, and in much greater numbers than their percentages of the population? Based on our studies of policing in New York and other cities, we do not think the arrests are mostly a result of personal bias or racism on the part of individual patrol officers and their immediate supervisors. Rather, this is a system-wide phenomenon, occurring in cities and counties throughout California. Police departments deploy most patrol and narcotics police to certain neighborhoods, usually designated "high crime." These are disproportionately low-income, and disproportionately African American and Latino. It is in these neighborhoods where the police make most patrols, and where they stop and search the most vehicles and individuals, looking for "contraband" of any type in order to make an arrest. The item that people in any neighborhood are most likely to possess, which can get them arrested, is a small amount of marijuana. In short, the arrests are ethnically- and racially-biased mainly because the police are systematically "fishing" for arrests in only some neighborhoods, and methodically searching only some "fish." This produces what has been termed "racism without racists."

But Levine et al. also argue that downgrading possession of an ounce or less of marijuana from a misdemeanor to an infraction, as legislation signed by Gov. Arnold Schwarzenegger a few weeks ago does (effective in January), will not eliminate the problem:

Both misdemeanors and infractions are results of routine policing practices which disproportionately focus on low-income black and Latino neighborhoods and their young people. Police departments have "productivity goals" (or quotas) for the summonses and arrests that patrol officers should make. Because the routine police stops are much more frequent in black and Latino neighborhoods, they unfairly produce more marijuana infractions and misdemeanors for young people in those neighborhoods. And this goes on despite the fact that U.S. government studies repeatedly find that young whites use marijuana at higher rates than young blacks and Latinos. None of this will change because of the new legislation. If young people stopped by police are found to have a bit of marijuana in their pockets or possessions, and do not have sufficient identification papers, they can still be handcuffed and taken to the police station to check their fingerprints on a database. In the course of the police stop, the officers may add other charges including disorderly conduct or resisting arrest. In 2009 the New York Times reported that police in San Jose, California made many arrests in which the only charge was "resisting arrest." Latinos are 30% of San Jose's population, but Latinos were 60% of the people arrested when "resisting arrest" was the only charge.

Unless Proposition 19 passes, possessing a small amount of marijuana will remain a pretext for being hassled by the police, and blacks and Hispanics will continue to suffer disproportionately from the resulting inconvenience, expense, and indignity.

I discussed Levine's research on New York City pot arrests in a 2008 column.