"It is the grand jury’s function not ‘to enquire … upon what foundation [the charge may be] denied,’ or otherwise to try the suspect’s defenses, but only to examine ‘upon what foundation [the charge] is made’ by the prosecutor. Respublica v. Shaffer, 1 Dall. 236 (O. T. Phila. 1788); see also F. Wharton, Criminal Pleading and Practice § 360, pp. 248-249 (8th ed. 1880). As a consequence, neither in this country nor in England has the suspect under investigation by the grand jury ever been thought to have a right to testify or to have exculpatory evidence presented."
-Antonin Scalia, United States v, Williams, 504 U.S. 36 (1992)
(Bolding by me, following the bolding at Hullabaloo)
The Darren Wilson grand jury was an illegal sham designed to exculpate a white man who murdered a black teenager. This prosecutor was involved in raising money for Darren Wilson's defense, and if he had a shred of morality would have recused himself from the case. Instead, he knowingly rigged the proceedings to produce this result.
In the decision of the court in this exact same case, Justice Scalia wrote that the double jeopardy clause of the fifth amendment does not apply to grand jury proceedings, and another grand jury is free to indict Darren Wilson in the future. That is what should be done to correct this horrible abuse of the justice procedure, but I guess there is not much hope of that.
And while they are at it, the prosecutor in this case needs to be removed from his position and thrown in jail. There is absolutely no excuse for this sort of misuse of his privileged position.
Correction: Gene informs me in the comments that my allegations about the prosecutor raising money for Darren Wilson are false. Here is a Snopes article about the subject. The article shows a screen shot of a website selling T-shirts to raise money for Darren Wilson. On the website is prominently displayed the logo of an organization called "Backstoppers," of which this prosecutor happens to be the President. After all the public attention, this organization claims to have nothing to do with the T-shirt sales, and the people who were involved are unknown. Snopes categorizes the story as a "mixture of true and false," but I guess there is no smoking gun there. Think what you want.