During an appearance on Hot 97 radio Monday morning, Mayor de Blasio said there's nothing that Donald Trump can directly do to fully reinstitute stop-and-frisk in New York City, a practice Trump once said "worked very well in New York." (It didn't.)

"The unconstitutional use of stop-and-frisk didn't make us safer," de Blasio said. "It was not only morally wrong, it actually did not make us safer."

"The federal government cannot tell a local police force to use a policy like that if we believe it's wrong for our city and our people," de Blasio continued. "They can threaten to take away our money, but they cannot tell us how to police our streets, and we are not going back to a broken policy of stop and frisk. That will not continue on my watch." The NYPD currently receives upwards of $200 million in federal antiterrorism funding alone.

Trump has said that he wants to cancel all federal funding to Sanctuary Cities—cities that have policies designed to not prosecute people solely for being undocumented immigrants—including New York City.

He also wants to introduce the Restoring Community Safety Act, which "reduces surging crime, drugs, and violence by creating a Task Force On Violent Crime and increasing funding for programs that train and assist local police."

During a September town hall on Fox, Trump said that he would fight crime be restoring stop-and-frisk not only in New York City, but nationwide. "We did it in New York, it worked incredibly well and you have to be proactive, and, you know, really help people sort of change their mind automatically," Trump said.

A week later, during the first presidential debate, Trump again claimed that the policy "brought the crime rate way down" in New York City. When moderator Lester Holt said that the policy was ruled unconstitutional for singling out black and Latino men, to which Trump responded that the allegedly successful policy was actually discontinued by Mayor de Blasio and "a very against-police judge."

Trump was wrong on multiple counts. Statistics from the NYPD show that black and Latino New Yorkers are overwhelmingly targeted by the practice, and that nearly 90 percent of stops between 2002 and 2015 were deemed innocent. The majority of the people who were arrested after being stopped were charged with minor crimes like possession of marijuana.

Homicides in NYC have decreased 32 percent since 2011, even after stop-and-frisk was reformed and rolled back—not ended—by federal judge Shira A. Scheindlin.