A NEW REPORT prompted by the huge overrepresentation of blacks and Latinos in Massachusetts prisons zeroes in on disparities at various stages of the court system’s handling of cases that are factors behind the disparate incarceration rates.

The report, commissioned by Supreme Judicial Court Chief Justice Ralph Gants and carried out by researchers at Harvard Law School, found that among those who are incarcerated, black and Latinx defendants receive sentences that are, on average, about five months longer than sentences for white defendants. Meanwhile, white defendants are more likely than black and Latinx defendants to have cases resolved through pretrial probation or other dispositions that don’t lead to incarceration. 

Four years ago, Gants highlighted the huge racial disparities in incarceration rates in his annual address on the state of the judiciary, and announced that Harvard Law School dean Martha Minow had agreed to launch an independent evaluation of the factors driving those inequities. 

In the report released on Wednesday, researchers from the Criminal Justice Policy Program at Harvard Law School found that racial and ethnic differences in the type and severity of the initial criminal charge against defendants account for over 70 percent of the disparities in sentence length. 

“The initial charging decision is in fact a huge driver of these large disparities in who is incarcerated,” said Felix Owusu, a Harvard PhD student and co-author of the report.

It was already well known that people of color are overrepresented in Massachusetts state prisons. A 2014 report of the Massachusetts Sentencing Commission found that the state was imprisoning black people at a rate of 7.9 times that of white people and Latinx residents at 4.9 times the rate of whites. 

The new report, using administrative data from the Massachusetts Trial Court, Department of Criminal Justice Information Services, and Department of Correction, attempts to break down racial disparities at various points as defendants move through the legal system. 

The Trial Court provided researchers with information for every Boston Municipal Court and District Court criminal case with at least one charge filed and disposed from January 2014 through the end of 2016.  There were 553,801 cases assessed in the study involving about 325,000 white defendants, 101,000 Latinx defendants and 94,800 black defendants, with the rest listed as “other.”

While whites account for 74 percent of the state population, they make up only 58.7 percent of the cases handled over this period. By contrast, blacks make up 6.5 percent of the state’s population but account for 17.1 percent of criminal cases in the study. Latinx people make up 8.7 percent of the population and 18.3 percent of cases.

Among those being sentenced to prison time, black and Latinx defendants received sentences that were, on average, 168 and 148 days longer than sentences given to white defendants. When the researchers took into account the severity of initial charges, the defendant’s criminal history, and other factors, the sentencing disparity was significantly smaller, but black and Latinx defendants still received sentences that were 31 and 25 days longer than whites.  

The researchers wrote in their report that they were unable to answer one fundamental question raised by the disparate representation of blacks and Latinos in the criminal legal system — “the extent to which aggregate differences in initial type and charge severity across racial groups reflect police and prosecutor discretion versus differences in criminal conduct.” 

The state’s tiered trial court system sends more serious cases to the Superior Court, while less serious cases are heard in District or Boston Municipal Court. Some cases fall in an area of “concurrent jurisdiction,” in which they could be tried in either court. 

The study found that black and Latinx defendants were more likely to have cases end up in Superior Court, where longer sentences are given, both because of the greater likelihood they faced charges exclusively handled by Superior Court and because prosecutors were more likely to indict their cases to Superior Court in instances where they have discretion to send cases there or handle them at the lower-level district court. 

“A major takeaway for me from this is prosecutorial power in charging decisions,” said Rahsaan Hall, director of the Racial Justice program at the ACLU of Massachusetts.

Black and Latinx people charged with offenses carrying a mandatory minimum sentence, like more serious drug offenses, wound up convicted and sentenced to incarceration at twice the rate of whites. Black and Latinx defendants accounted for more than 70 percent of the people charged with carrying a firearm without a license and leaving a firearm unattended.

Black defendants face murder charges at a rate over six times higher than whites, but are also more likely to have their initial murder charges reduced to manslaughter or a different final charge that carries a lesser mandatory minimum sentence.

“It shows that prosecutors exercise their discretion in a way that is racially disparate,” said Hall, a former prosecutor. He said that suggests to him that prosecutors are “overcharging” defendants in an effort to get them to plead guilty to a reduced charge.

The study found that whites are more likely to face charges in district court, such as driving under the influence, that can result in a disposition other than incarceration. More than 82 percent of people convicted of operating under the influence in Massachusetts were white, and 80 percent of those cases were resolved without incarceration, mostly through a “continuance without finding,” which allows the offender to ultimately not have a guilty finding on their criminal record.

In 80 percent of cases, defendants were released before trial on their own recognizance. Overall, bail was imposed in a slightly higher percentage of cases involving black and Latinx defendants compared white defendants. 

Gants was hospitalized on Friday with a heart attack, but released a statement on the study through the court system spokesperson. “This impressive report will provide us with important guidance as we work to eliminate racial and ethnic disparities in the Massachusetts criminal justice system,” he said. “It is a ‘must read’ for anyone who is committed to understanding the reasons for such disparities and taking action to end them.” 

The researchers said there were some significant gaps in their study data. Researchers requested arrest data from every local police department, but most did not respond or provide data. Similarly, they requested prosecutor data through the Massachusetts District Attorney Association, which did not provide information. One DA offered unusable data, another said it would have taken too long to provide the requested information, according to the report.

Two sheriffs, who were not named, also didn’t provide requested data about people sentenced to houses of correction, which are overseen by local sheriffs. Researchers also said it was challenging to track cases that move from Municipal and District Court to Superior Court, because they could appear in data twice. 

The lack of information from law enforcement limited the study’s ability to assess disparities in policing practices and arrests that determine who enters the court system. The authors point out that other studies have shown big racial disparities in traffic stops and initial police interrogations leading to people being frisked. 

“Both national and Massachusetts-specific studies find substantial racial disparities in policing practices,” write the authors, “suggesting that our results based on available data following the filing of charges may underestimate the true magnitude of racial disparities in the Massachusetts criminal justice system.”