At this writing, Chicago is the latest city to erupt in protests. The impetus there is yet another gruesome video, this time of an officer named Jason Van Dyke shooting 17 year-old LaQuan McDonald 16 times as he walked away from police.
The public wouldn't know the truth even about McDonald if not for a Freedom of Information Law (FOIL) request filed by journalist Brandon Smith. We also wouldn't know that Van Dyke had over 20 abuse complaints in his past, were it not for the Citizens Police Data Project (CPDP), which is undertaken by a group called the Invisible Institute in conjunction with the Chicago Law School's Mandel Legal Aid clinic. The group used FOIL and litigation to obtain information about abuse complaints of thousands of officers.
But Chicago is the exception, while New York is closer to the rule. In the Garner case specifically, similar efforts have been undertaken to dig up the dirt, but this city has been more successful in keeping it hidden.