During an interview for "This Week," New York City Police Commissioner Ray Kelly warned that the ruling by a federal judge declaring the way his department carries out its "stop-and-frisk" policy unconstitutional risked reversing the downward trend of violent crime in New York City.

"What we're doing - and what we're trying to do - is save lives," Kelly told ABC's Pierre Thomas.

"Things are going right here in New York. And this decision certainly has the potential of overturning it," he said.

During the interview, Kelly rejected the ruling by U.S. District Judge Shira Scheindlin, who declared that the NYPD policy had resulted in "indirect racial profiling" - with blacks and Hispanics - who make up the majority of those stopped by police under the "stop-and-frisk" policy - being unfairly targeted. Of the approximately five million stops over the past decade, about 10 percent result in arrest according to The Associated Press.

For his part, the police commissioner defended the execution of the policy by his department.

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"You have to apply a formula of sorts. 'Do the stops comport with the description given by the victims of perpetrators of violent crime?' And our stops certainly do," Kelly said.

"Nobody wants to be stopped…we have engaged in a major training evolution for several years, focusing on these issues, to do these stops with courtesy, do them with respect," he added.

Scheindlin ruled the "stop-and-frisk" policy could continue with federal oversight and certain fixes. But Kelly expressed skepticism on one of the remedies ordered, which involves certain officers wearing body cameras.

"When do you turn the camera on? When do you turn it off?" Kelly asked. "Do you have it on when somebody comes and wants to give you confidential information?"

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