A federal judge appointed an independent monitor Monday to oversee changes to the New York Police Department’s contentious policy known as stop and frisk after finding it intentionally discriminates based on race, a significant judicial rebuke for what the mayor and police commissioner have defended as a life-saving, crime-fighting tool. U.S. District Court Judge Shira Scheindlin said in a ruling that Peter L. Zimroth, a onetime city lawyer and a former chief assistant district attorney, has been appointed as the monitor. In both roles, Zimroth worked closely with the NYPD, the judge said. The judge accused the police department’s senior officials of violating law “through their deliberate indifference to unconstitutional stops, frisks and searches.” “They have received both actual and constructive notice since at least 1999 of widespread Fourth Amendment violations occurring as a result of the NYPD’s stop and frisk practices. 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. She also cited violations of the Fourth Amendment protection against unreasonable search and seizure. “Far too many people in New York City have been deprived of this basic freedom far too often,” she said. “The NYPD’s practice of making stops that lack individualized reasonable suspicion has been so pervasive and persistent as to become not only a part of the NYPD’s standard operating procedure, but a fact of daily life in some New York City neighborhoods.” Four men had sued, saying they were unfairly targeted because of their race. There have been about 5 million stops during the past decade, mostly black and Hispanic men. Scheindlin issued her ruling after a 10-week bench trial for the class-action lawsuit, which included testimony from top NYPD brass and a dozen people – 11 men and one woman – who said they were wrongly stopped because of their race.