Arrests of young people dropped by two-thirds in Massachusetts over roughly the past decade, but people of color made up an increasing share of those arrests in the same span, according to new research.

In an analysis of federal data, researchers with the Emerging Adult Justice Program at Columbia University's Justice Lab said they found a pair of noteworthy trends in the Bay State that moved in opposite directions between 2013 and 2022.

The number of arrests of Massachusetts residents under the age of 21 dropped 67 percent over that span, researchers found. At the same time, racial inequalities deepened, with Black and Hispanic or Latino young people representing a larger share of arrests in 2022 than in 2013.

"We are calling this the 'Good News/Bad News' study, because the arrest reductions show that crime is decreasing and more young people are thriving in our communities," said Lael E.H. Chester, director of the program. "The representation of Black and Hispanic/Latinx youth rose, however, and research suggests that's not because young people of different races are behaving differently -- it's because our systems treat them differently."

How the criminal justice system treats young adults has increasingly emerged as a point of debate for policymakers. The Massachusetts Supreme Judicial Court last month ruled that it is unconstitutional to sentence defendants to life without parole for crimes they committed when they were 18, 19 or 20.

Authors with Columbia's Justice Lab linked their findings to pending legislation (H 1710 / S 942), filed by Reps. Jim O'Day and Manny Cruz and Sen. Brendan Crighton, that would redirect 18-, 19- and 20-year-olds to the juvenile justice system for many offenses.

"While raising the upper age of juvenile court jurisdiction cannot alleviate the racial inequalities perpetuated by disproportionate arrest rates and other systemic inequalities, it does serve to mitigate some harms produced by the criminal legal system, providing a safer and more restorative system for Massachusetts' emerging adults," they wrote.