IIRC, almost all of the witnesses who lied to the grand jury - I think there was just one exception - were "eye-witnesses" who accused Officer Wilson of shooting Brown, variously: in the back; while Brown was kneeling; while Brown was laying on the ground; while Brown had his hands in the air. All of which were proven false by forensic evidence such as the autopsy and crime scene evidence ... evidence the Prosecutor also presented to the grand jury.
Imagine the outcry had the Prosecutor not had all those known-liar witnesses testify!
The real beef the race-baiters have with what the Prosecutor presented to the grand jury is that he presented all the evidence, not just the evidence that would make an indictment likely. Well, gee! A prosecutor who wanted justice rather than an indictment? A prosecutor who wanted to be sure he had a solid case rather than one that would get laughed out of court in a criminal trial? How shocking!
IMO, unless the ACLU judge-shopped very carefully before making this move, they're going to have their all-too-substantial @#$es handed to them.