Public opposition to marijuana arrests surfaced during the 1970s, when affluent families complained to lawmakers after seeing the future careers of their children ruined by petty marijuana arrests. The Legislature subsequently barred the police from arresting people for tiny amounts of the drug, unless it was being smoked or shown in public view. Black and Latino communities have since borne the brunt of the enforcement policy.

Mayor Bill de Blasio, who took office three years ago, put into place the policies that have reduced the number of people arrested each year for trivial amounts of marijuana. Instead of being hauled off to jail, many people found with small amounts are given summonses and allowed to continue on their way. As a result, the de Blasio administration is averaging about 20,000 marijuana arrests per year, about half the average of the Bloomberg years.

Nevertheless, a new analysis by Harry G. Levine, a sociology professor at Queens College, shows that longstanding racial disparities have persisted. African-Americans and Latinos make up about half the population, but, as in decades past, they make up about 85 percent of those arrested for low-level marijuana offenses.

The Police Department argues that the arrests occur in places where it receives drug complaints. But the study shows that arrests are strikingly skewed along racial lines everywhere in the city.

African-Americans are arrested at 15 times the rate of whites in Staten Island and in Manhattan, and seven times the rate of whites in Queens. The disparities shown in the analysis are especially striking in areas where African-Americans make up a small proportion of the population.