Mayor de Blasio has reformed the way the NYPD treats marijuana possession and recently rolled out his "Justice Reboot" plan to depopulate Rikers Island and streamline the summonsing process. Yet Bloomberg's albatross remains: how do you justify a leftover system of aggressive, racially disproportionate police tactics when crime and incarceration rates continue to fall?

If you're NYPD Commissioner Bill Bratton, you scold Millennials for not existing when the public literally begged him to arrest as many people as he could.

"They did not experience the New York of 1990," Bratton told law enforcement donor John Catsimatidis yesterday, referring to the majority of 18 to 34 year-olds who oppose his approach to policing low-level crimes.

Bratton has built his reputation and his fortune on Broken Windows policing, and insists that the city's safety depends on its survival.

"They're experiencing the New York of 2015, which is a beautiful city, a safe city. That population group were not even alive, many of them, in 1990 when this city was going to hell in a hand-basket."

But these Millennials were alive during the stop and frisk era, in which millions of young men of color were subjected to unconstitutional, racially biased policing that did not seem to comport with the "safe city" they were living in. It's no wonder they are more wary of the police.

Commissioner Ray Kelly promised that if the NYPD's use of stop and frisk were to "change significantly…people will die as a result." Instead the murder rate continued to decline, even after stops were reduced by around 90%.

Mayor de Blasio seems to acknowledge that he will have to pull Bratton into the 21st Century, as he did eight months after the commissioner called decriminalizing marijuana "a major mistake." Bail and summons reform followed; the administration is even discussing the idea of offering amnesty for decades-old warrants that clog the system.

According to a report in the Times, this isn't enough for many leaders of the black community, who held a meeting last week on "What to do about Mayor Bill de Blasio."

City Councilman Jumaane D. Williams, a police reform advocate who said he had a positive working relationship with the mayor, said there was nearly “universal” agreement that changes to law enforcement had been slow in coming. “As time passes on and things are moving at a pace slower than people wanted, I think everyone is going to begin pushing a little bit more,” Mr. Williams, a Brooklyn Democrat, said.

The challenge from the mayor's base comes as a class-action lawsuit against the city plods towards trial.

One-fifth of all the 3.8 million summonses handed out by the NYPD between 2007 and 2014 were tossed out, which was a enough for a federal judge to note that the practice was "tantamount to a decision that probable cause was presumptively lacking," according to the Times. The trial will begin next year.

"A lot of us were here in the 1980s, 1990s, and could never have imagined these kind of numbers," the mayor told reporters in January, lauding the decreases in crime. "They are the result of a proactive strategy. They're the result of a number of strategies, one of which is the Broken Windows approach."