Shootings are up 20 percent this year. Bratton is blaming marijuana. I doubt it. But maybe. I'm certainly willing to consider the idea. Most liberals, I find, never ever consider the idea that their advocacy might have unintended consequences, like more young black men getting murdered.
That said, Bratton pointed to drug dealers getting killed. That was illegal last year and remains illegal this year. So I'm not certain how not arrested people for small scale marijuana possession really changes anything. (For public safety or Broken Windows, that is. It certain matters for the guy getting arrested or not.) If the increase is as Bratton describes it, these killings seem more like old-fashioned Prohibition killings than decriminalization killings.
But... it could be that criminals are more brazen in response to less aggressive policing. And maybe some robber smoking a joint last year would have gotten stopped by the po-po. But not so in 2015. I'm not saying that is the reason. But it's possible.
Here's the story in the Times. Worth reading if you're into this kind of thing.