Black students at New York City's public schools are arrested at a rate 10 times higher than their white peers, according to a new report on school discipline from the New York Civil Liberties Union.

The report, which was released Friday, found that more than 60 percent of in-school arrests made in the first half of 2016 were of black students, even though less than 30 percent of students in NYC schools are black. The arrest rate for black students was more than 2.5 times the rate for Latinos.

White students make up 15 percent of the public school population but accounted for only 3 percent of arrests in the period examined. Latinos, who make up 40 percent of the population, accounted for 30 percent of arrests.

According to the NYPD, the total index crime in schools has decreased 35 percent over the last five years. That has corresponded with a decrease in enforcement actions. Arrest and summons rates, the NYCLU report found, dropped 37 percent and 10 percent, respectively, since 2015.

But critics say the rates of major disciplinary action are still far too high.

"As summonses and arrests of students go down and school safety goes up, it is clear that frequent reliance on aggressive discipline is unnecessary and especially harmful to black and Latino students," NYCLU Executive Director Donna Lieberman said in a statement. "We expect our schools to be safe and supportive for all our children."

The NYCLU found that although suspension rates have decreased, schools continue to lean heavily on suspensions instead of less aggressive disciplinary actions like parent conferences or detentions. Only 15 percent of suspensions issued during the 2015-2016 school year were for "serious infractions"—which under DOE rules require automatic suspension. The remaining 85 percent of suspensions were made at the schools' discretion.

Black students were issued suspensions at far higher rates than other students. Of the 37,647 suspensions issued in the 2015-16 school year, half were issued to black students. White students accounted for just 8 percent of suspensions during this period.

According to the DOE, suspensions of black students students decreased by 19 percent between the 2014-15 academic year and 2015-16 academic year. (Suspensions dropped 9 percent for white students.)

The NYCLU report also shows that virtually every instance of a mental health emergency in which police were called involved a black or Latino student. "It would appear that any time a black or Latino student is having a mental health crisis, schools' first response is to call the cops," NYCLU advocacy director Johanna Miller said in a statement.

"We're encouraged by the steady decrease in suspensions along with crime, summonses and arrests, and are dedicated to continuing this essential work to ensure all students feel safe and are ready to learn," said DOE spokesperson Toya Holness. Holness did not comment on the high suspension rate among students with individualized education plans—18.7 percent of students in NYC public schools have IEPs, but students with IEPs accounted for 38.6 percent of all suspensions in the 2015-16 school year.

A NYCLU report from 2013 argued that schools' reliance on law enforcement to enforce discipline criminalizes students and undermines schools' educational mission.