Just because it failed once, doesn't mean it's pointless. The more it happens ("Gee, the last 7 mayors elected promising police reform were raided, none of the others were...") the more obvious it gets, and the harder it will be for police officers to look their friends and family in the eye while not standing up to such blatant corruption. That's not to say it's the only thing we should be doing, but it's something we should be doing.