However, in the ruling, Judge Shira A. Scheindlin stops short of calling for eliminating stop-and-frisk, but instead says she is reforming it. The independent monitor will oversee changes to the NYPD policies, training, supervision, monitoring and discipline.
"The city's highest officials have turned a blind eye to the evidence that officers are conducting stops in a racially discriminatory manner," she wrote. "In their zeal to defend a policy that they believe to be effective, they have willfully ignored overwhelming proof that the policy of targeting "the right people" is racially discriminatory."
The ruling stems from the case of four men who say New York City police unfairly targeted them because of their race. There have been about 5 million stops during the past decade, mostly of black and Hispanic men.
People who Eyewitness News spoke to in Harlem Monday night say the judge got it right.
"They only pick the Latinos and blacks," said Harlem resident Michael Long.
Leroy Jones, another Harlem resident said that stop and frisk was unconstitutional and an "invasion of privacy".
Crime Commission President Richard Aborn says the stops will become more effective under the changes.
"So what will change is probably more training of officers around how they can stop people, why they can stop people, and what they have to say when they stop people," Aborn says.
Mayor Michael Bloomberg blasted the judge's ruling, saying he will file an appeal.
"It has taken some 8,000 guns off the street over the past decade, and some 80,000 other weapons," Bloomberg said.
Police Commissioner Ray Kelly says the practice has saved thousands of lives without racial profiling.
"What I find most disturbing and offensive about this decision is the notion that the NYPD engages in racial profiling. That is simply recklessly untrue," Kelly noted.
"We didn't believe that we were getting a fair trial," the mayor said. "And this decision confirms that suspicion."
Bloomberg and Kelly have long defended the practice, repeatedly arguing that the city's historically low crime rate was proof that stop-and-frisk works.
In a recent Nightline story, Kelly and Bloomberg argued that hundreds of thousands of seemingly fruitless stops are proof that stop-and-frisk works; that the policy is an effective deterrent and New York City kids know better than to walk the streets with a gun. Kelly also argued that since 75% of crime victims describe their attackers as black or Hispanic, young men of color are proportionately under-stopped-and-frisked in the City.
"Many police practices may be useful for fighting crime - preventive detention or coerced confessions, for example - but because they are unconstitutional they cannot be used, no matter how effective," Scheindlin wrote in her ruling.
The judge found that senior officials in the city and the NYPD were deliberately indifferent to officers conducting unconstitutional stops and frisks.
The judge said "the policy encourages the targeting of young black and Hispanic men based on their prevalence in local crime complaints. This is a form of racial profiling." She said "the City is liable for violating plaintiffs' Fourth and Fourteenth Amendment rights."
Scheindlin concluded that the plaintiffs had "readily established that the NYPD implements its policies regarding stop and frisk in a manner that intentionally discriminates based on race."
She also cited violations of the Fourth Amendment protection against unreasonable search and seizure.
Scheindlin said, through paperwork alone, she determined at least 200,000 stops were made without reasonable suspicion, the necessary legal benchmark, lower than the standard of probable cause needed to justify an arrest.
City lawyers argued the department does a good job policing itself with an internal affairs bureau, a civilian complaint board and quality assurance divisions.
Police brass received warnings since at least 1999 that officers were violating rights, she said. "Despite this notice, they deliberately maintained and even escalated policies and practices that predictably resulted in even more widespread Fourth Amendment violations," she wrote in a lengthy opinion.
Scheindlin appointed Peter L. Zimroth, a onetime city lawyer and a former chief assistant district attorney, to oversee the reforms. In both roles, Zimroth worked closely with the NYPD, the judge said.
According to NYU's Brennan Center for Justice, Zimroth is also an accomplished trial lawyer and appellate advocate and is recognized as a leading litigator in products liability, commercial, securities, and white collar crime matters.