But the laws didn't start working until police effectively started enforcing them, said Zimring, a law professor at the University of California, Berkeley.

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Minority communities, Zimring emphasizes, paid a disproportionate price in kids stopped and frisked, and detained, but they also earned a disproportionate gain in crime reduced.

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Zimring also touches upon the role of aggressive, stop-and-frisk policing in the violence decline, though he notes its impact is small, its costs potentially large.

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