"Although we are not aware of any data tracking the precise rate at which people of different races play cards or dice, it is extremely unlikely that African Americans comprise 99 percent of those doing so," the authors note.
Ostensibly, zero-tolerance policing is a thing of the past in Baltimore. Martin O'Malley, the former mayor, instituted the policy after taking office in 1999. Under O'Malley, officers were making some 100,000 arrests a year in Baltimore, a city of about 650,000 at the time.
Since then, Baltimore officials have retreated from the policy, but the Justice Department contends the practice has persisted. And if Baltimore's police have zero tolerance for public disorder, they somehow have even less tolerance for offenses in black neighborhoods, the report implies.
For his part, O'Malley argues the policies helped reduce crime. "None of it was easy," he told The Washington Post last year. "All of it was hard. But there were very few people who want to return to those violent days of 1999."
The report presents data on some of the vaguely defined misdemeanors that give police officers in every city substantial leeway over whether to make an arrest. In Baltimore, black residents were twice as likely to be charged with failing to obey an officer and nearly three times as likely to be charged with disorderly conduct.
Prosecutors and booking officials, however, threw out many of these charges immediately, indicating they either viewed the accusation as baseless or thought the offense was too minor to merit prosecution.
As an example, more than 1 in 4 charges of disturbing the peace against black suspects were dismissed on initial review. Officials dismissed just 1 in almost 20 charges against white defendants for the same offense.
For some experts, these statistics show officers' sincere efforts to maintain order, with the goal of preventing violence in the city's most dangerous neighborhoods. For others, they are the consequences of a policy that provides police with too much leeway, gives too little attention to civilians' rights and allows individual officers' racial biases to influence law enforcement.
Charles Epp, a political scientist at the University of Kansas, said the data on Baltimore fits a familiar pattern. He and his colleagues' own research in Kansas City also show that officers are more likely to use their discretion to stop black drivers than white drivers.
"This is a pattern that is extraordinarily widespread and deep," Epp said. "Over the long term, these stops — carried out month after month, year after year — powerfully erode trust in the police and, in fact, also more broadly erode trust in the fairness of the legal system."
As a result, he added, people become less likely to call the police for help or when they have information, which could increase crime over the long term.
"It undermines the ability of officers to gain cooperation from the community," said Jack Glaser, a psychologist at the University of California at Berkeley. "If they’re engaged in that kind of aggressive policing, any — even small — racial biases in their decisions about who's suspicious are going to get magnified."
Studying the consequences of different policing strategies is difficult for criminologists because the details of implementation vary from city to city, and because so many other factors influence crime. The available evidence suggests that strategies of strictly policing minor crimes can reduce crime in general if they are focused on specific problems that are truly connected to violence.
Peter Moskos, a former Baltimore officer who is now a sociologist at the John Jay College of Criminal Justice in New York, said he opposes zero-tolerance policing for that reason. Indiscriminately arresting people for minor violations does not necessarily reduce crime, he said.
In particular, he argued, the Baltimore Police Department rewards units that record as many bookings as possible, encouraging officers to make arrests without regard to whether they are really necessary.
At the same time, Moskos also argues that police justifiably enforce the rules against minor offenses if doing so helps them control behaviors that carry a real risk of lethal violence.
As an example, Moskos said police officers view dice in public a potential cause of violence, not just a public nuisance. That attitude could be why, earlier this year, officers on a police helicopter called in the patrol when they spotted people playing dice in public from the air, according to the report.
"People really don’t like losing money at dice," Moskos said. "You got to break up those games, because eventually somebody’s going to get angry."
In this respect, the issue of gambling epitomizes the controversy over the racial implications of these policing strategies. Police do not break up groups of young white men playing poker in the basement of their parents' houses in the suburbs, but they regard young black men shooting dice on the street corner as dangerous.