Blacks are significantly more likely than whites to be arrested in Minneapolis for low-level crimes such as marijuana possession and loitering, according to a new study.

The report, released Tuesday by the American Civil Liberties Union of Minnesota, said that blacks are 11.5 times more likely to be arrested for marijuana possession, even though advocates say that white and black people use the drug at similar rates.

The research also showed that blacks are nearly nine times more likely to be arrested for disorderly conduct in Minneapolis than whites. The racial disparities for the rates of arrest for vagrancy (7.54 times more likely) and for minors violating curfew or loitering (16.39) are equally stark, according to the report that was based on arrest data from the Minneapolis Police Department.

"What might be viewed as a noisy argument between two white people, might become disorderly conduct when it's between two black people," said Teresa Nelson, legal director for the ACLU's local chapter.

Nelson said the research revealed "implicit biases" in the way laws against low-level offenses are enforced and blamed the disparity on racially biased policing strategies.

Minneapolis Police Chief Janeé Harteau said that her department would further analyze the study's findings.

"I will ask the department's analysis unit to examine this and areas such as victimization, location of crime, and reported suspect information," Harteau said. "These and other areas need to be examined before making an assessment on the effectiveness of improving public safety and public trust."

Nelson said the disparities may be a messy byproduct of the department's "broken windows policing," the strategy of relentlessly cracking down on minor crimes to deter more serious ones.

"This focus on low level offenses as a strategy to get at and maybe head off more violent crimes, I think it does lead to these disparities," ­Nelson said. "These are subjective offenses."

At a recent community forum on the North Side, black and Latino residents complained of being targeted by police officers on W. Broadway because of their race. Often, they said, the ­officers would confiscate their IDs without cause.

The study, which drew on arrest data from 2004 to 2012, showed that 436 in 100,000 blacks were arrested for vagrancy in 2012, compared with 73 in 100,000 whites. In 2004, the ratio was 188 in 100,000 blacks to 44 in 100,000 whites, the data shows.

The racial disparities in marijuana possession arrests actually decreased since 2006, the data shows, but blacks with pot were still 6.89 percent more likely to be jailed than whites.

Nelson cautioned that because Latinos are lumped in with whites, the racial gulf may be even wider.

ACLU officials sent a letter to Harteau and Mayor Betsy Hodges urging them to honor their commitment to "undertake a much-needed assessment and analysis of how to improve the" police department.

"Everyone in Minneapolis deserves to feel safe, be safe, and be treated equitably in every neighborhood," said Hodges, whose administration has championed racial equality in all corners of the city.

The mayor said that she was concerned by the report's findings and would take its recommendations seriously.

The department has in recent years worked to improve its reputation for racial insensitivity, providing cultural awareness training and beefing up community outreach.

In 2013, the chief asked the U.S. Justice Department to evaluate the department's officer oversight and discipline process, and the ensuing report called for a more data-driven approach to helping supervisors identify problem cops and provide them with additional training.

Heather Martens, head of Protect Minnesota, an organization trying to end gun violence, said the level of racial disparities in low-level arrests erodes the trust that's needed for effective policing and keeping the community safe.

The new study piggybacked on the findings of a major ACLU report that revealed that Minnesota in general and Hennepin County in particular had among the nation's highest disparities in marijuana arrests.

Libor Jany • 612-673-4064 Twitter:@StribJany