While it's true that most grand juries serve as a rubber stamp for prosecutors, what so many seem to be ignoring is that in most cases where a prosecutor has doubts or lacks faith in the case, she or he doesn't present the case to a grand jury at all. Prosecuting Attorney Robert McCulloch was under no obligation to present the case to any grand jury. As many prosecutors, particularly in police shooting cases, have done before him, he could have simply determined there was insufficient evidence to take the case to trial and ended it there. Typically, if a prosecutor reviews all the evidence and becomes convinced she/he doesn't have a solid case, the case concludes with no charge and no grand jury ever reviews the case.
I wouldn't presume to know exactly what Mr. McCulloch thought when he began the process, but I would not be surprised to learn that he had doubts about the evidence against Officer Wilson but felt pressure to have an objective body review the evidence so he did not have to assume the responsibility for such a monumental and controversial decision himself. If true, that is not a scandal but rather exactly what one would hope a prosecutor in his shoes would do.
Now, that does not mean this prosecutor did not control how the evidence was presented to the grand jury. He did. But after reading through the grand jury material, it seems it was the evidence, not how it was presented, that likely swayed the grand jurors. Whatever one thinks about what really happened or how the process should have unfolded, the fact that we learned that the blood evidence matched up with Officer Wilson's account of Michael Brown coming at him and that some of the key eyewitnesses offering damning testimony against Officer Wilson contradicted the physical evidence, would have made it a herculean task to win a conviction against Officer Wilson.
