A wide range of changes to criminal sentencing laws that most states have adopted in the last two decades did not play a major role in the reduction of Black-white disparity in imprisonment seen between 2000 and 2020, according to a study released Thursday by the Council on Criminal Justice.

The Black-white incarceration disparity rate fell by 40% from 8.2-to-1 to 4.9-to-1 in 20 years, but not thanks to sentencing reforms, some of which were enacted with the explicit goal of narrowing the racial gap, the study's authors said.

During the same period, disparity in imprisonment between Black and white women decreased even more sharply — by 71% — from 6.3-to-1 to 1.8-to-1. The decline was driven by a 56% reduction in the imprisonment rate for Black women and a 57% increase for White women, according to the study.

"Troubling racial disparities persist in our criminal justice system, but the narrowing we've seen since the turn of the century is encouraging," Adam Gelb, president and CEO of the CCJ, said in a statement Thursday. "These new findings shed critical light on the path forward, showing us that we need to look beyond sentencing to identify the policy levers that can promote fairness and equity."

In the study — a collaboration between CCJ, Georgia State University and the Crime and Justice Institute — researchers looked at more than 700 sentencing reform laws enacted in 12 states between 2010 and 2020 trying to find a possible causal relationship between them and the racial disparity reduction.

Some of those laws involved penalties for certain offenses, others expanded alternatives to incarcerations, and a smaller number of reforms were passed to address racial and ethnic disparities. With minor exceptions, the study found, the reforms had negligible effects on reducing racial disparities. Rather, they codified into law shifts in criminal justice practice that were already happening in those jurisdictions.

In a call with Law360, Gelb said the findings in the study were "disappointing but illuminating."

"With so many efforts over such a long period of time to enact reforms that would close the disparity gaps, we would have hoped to see more impact. But that's not what the numbers showed," he said.

In many cases, changes in the law came only after changes had already started happening in practice, in the way that police, prosecutors, judges and parole boards were making their decisions, according to Gelb.

"We saw the law changes codifying rather than driving the changes," he said.

But on the other hand, the findings help criminal justice researchers, advocates and legislators pivot to strategies that could be more effective in reducing racial disparities in incarceration.

"We have to ground these conversations in facts," Gelb said. "If we don't make the right diagnosis, we're going to have the wrong prescription ... if the goal is to reduce disparities, and we need to know what is working and not working."

That means taking a hard look at whether sentencing reforms had any role in narrowing the prison population's racial gap, in particular in cases where that was the specific aim.

According to the study, the smallest reduction in incarceration disparities was observed in the population in prison for violent crimes, which represents about two-thirds of the population overall.

Thaddeus Johnson, a Georgia State University criminologist and CCJ senior fellow who co-authored a report coming at the end of the study, said that making progress in eliminating racial disparities in incarceration requires stemming violence in Black communities. It also requires taking a deep look at disparities in which penalties are imposed for similar crimes on Black and white people.

"We must confront the role of criminal history in sentencing and release policies, because Black people tend to have disproportionate contact with the justice system," Johnson said in a statement accompanying the report. "The reality is that unless we address historic and structural inequities in Black communities and grapple with the length of prison terms for serious violent crime, disparities will persist."

While concluding that sentencing reforms have little bearings on the decrease in racial incarceration disparity rates, the study's authors said other factors, including changes in policing practices, drug use, how drugs are sold and the types of crimes people commit, could have played a bigger role.

As part of a broader data analysis, the CCJ also found that disparity in imprisonment rates between Hispanic and non-Hispanic white people has declined during the first two decades of the century.

It's unclear, however, how much those rates have declined, in part because two sources have given increasingly conflicting results since 2000. Data collected from state corrections departments showed a Hispanic-white disparity ratio of 1.5-to-1 in 2020. In contrast, a federal prison survey found a ratio that was 80% larger: 2.7-to-1. The study attributes that divergence to significant differences in measurement methods between data sources.

Meanwhile, the Hispanic-white female imprisonment rate disparity fell by 56% over the same two-decade period, according to data provided by state corrections departments captured by the study. In 2020, the rate was 0.7-to-1, meaning that white women were more likely to be incarcerated than their Hispanic counterparts.

Overall, the largest drop in racial imprisonment disparity among women was observed in relation to drug crimes. The incarceration disparity between Black and white women for those offenses fell from 8-to-1 to 0.6-to-1 and reached parity in 2016. Disparity rate in the same context between Hispanic and white women fell from 2.4-to-1 in 2000 to 0.5-to-1 in 2020.

The trends were driven by changes in the demographics of the women who were incarcerated, the study says. From 2000 to 2019, the number of Black females admitted into prisons fell by 47%, while the number of white women who were put behind bars rose 138%, and that of Hispanic women increased by 15%.

Gelb said that the knowledge gained in the study will be helpful in crafting new plans to address disparities among incarcerated people. One area where to focus efforts is the difference in the rates of violence along racial lines.

"We know where to look, and that is toward the front end of the system, and particularly at reducing disparate levels of community violence," Gelb said. "We're not going to make further dramatic progress toward parity unless we reduce the disparate rates of community violence."

--Editing by Adam LoBelia.