The criminologist who helped develop the theory of "broken windows" policing and a top NYPD official appeared at the Rev. Al Sharpton's convention Wednesday to defend the practice, which some fellow panelists called unfair, counterproductive and racially discriminatory.

"I've learned my lessons sitting in living rooms and church basements, talking to citizens, many of them African-American or Hispanic, many poor whites as well. And they wanted order. They didn't want somebody peeing on their front steps. They wanted that taken care of," said George Kelling.

His 1982 article -- arguing that addressing minor disorder can deter major crime -- influenced a generation of police officials, including current NYPD Commissioner William Bratton. Kelling was on a panel at Sharpton's National Action Network conference at a midtown Manhattan hotel with Bratton's top deputy, Benjamin Tucker.

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Several of the panelists called for the NYPD and other agencies to abandon or curb the practice.

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"We police black communities differently. Period," said City Councilman Jumaane Williams (D-Brooklyn), a critic of the NYPD.

Tucker said his 35,000-member police force was being retrained, to stress quality enforcement over quantity.

"It takes a while," said Tucker. "You're talking about 35,000 people who have been living in a particular culture that's lasted more than a dozen years in many ways."

Separately, Mayor Bill de Blasio reinforced his support for broken windows policing. Speaking to reporters after appearing with Sharpton Wednesday morning, de Blasio said, "broken windows is a strategy that's worked."

A prominent Harlem clergyman, the Rev. Calvin O. Butts III said earlier this week said his support and that of other allies for de Blasio's re-election in 2017 could be in jeopardy if he didn't curb broken windows policing. De Blasio said he looked forward to meeting with Butts.