In the wake of the murders of two NYPD officers, arrests in NYC have plummeted.

Citations for traffic violations fell by 94 percent, from 10,069 to 587, during that time frame.

Summonses for low-level offenses like public drinking and urination also plunged 94 percent — from 4,831 to 300.

Even parking violations are way down, dropping by 92 percent, from 14,699 to 1,241.

Drug arrests by cops assigned to the NYPD’s Organized Crime Control Bureau — which are part of the overall number — dropped by 84 percent, from 382 to 63.

The latest official stats are here (PDF).

The police unions deny any coordinated work stoppage.

Mr. Bratton said on Monday that a “weeklong period of mourning” and demonstrations that were straining resources were contributing to the drop-off in arrests and summonses. But he said the slowdown should not concern New Yorkers. “I would point out it has not had an impact on the city’s safety at all,” Mr. Bratton said.

A top union official flatly denied that there was a job action and pointed to the orders to double up and the need to police demonstrations as the main reasons.

We rarely have such a stark change in public policy with which to analyze the effects in the real world. This is a case where a crude A/B test jump-started itself in the real world (it would be more useful if it were only specific precincts within NYC that saw this decline in arrests rather than all of them, but we can still look at the effects across cities). It will be interesting to look back in a few weeks and see if there are any new conclusions to be drawn about the broken windows policy.