Was there ever an OFFICIAL grand jury to whom this evidence was introduced, prior to making the indictment against George Zimmerman? Apparently not, as the indictment was brought by Angela Corey based on what was essentially hearsay evidence, and bypassing the grand jury altogether.
It has always been popularly supposed (particularly by those on the left) that a grand jury could return an indictment against a ham sandwich, if that was the outcome desired.
But given the weakness of the case, even this low standard was more than the grand jury could be trusted with.
Under Florida law, a certain degree of prosecutorial discretion is allowed, but not when there is potential for sentence for commission of a capital crime. Manslaughter would not be necessarily subject to grand jury review, but almost certainly, second-degree murder should have been beyond the discretion of the prosecutor.
If that's strue, then it is a violation of the FL Constitution:
FL CONSTITUTION, ARTICLE 1, SECTION 15. Prosecution for crime; offenses committed by children.—
(a) No person shall be tried for capital crime without presentment or indictment by a grand jury, or for other felony without such presentment or indictment or an information under oath filed by the prosecuting officer of the court, except persons on active duty in the militia when tried by courts martial.
(b) When authorized by law, a child as therein defined may be charged with a violation of law as an act of delinquency instead of crime and tried without a jury or other requirements applicable to criminal cases. Any child so charged shall, upon demand made as provided by law before a trial in a juvenile proceeding, be tried in an appropriate court as an adult. A child found delinquent shall be disciplined as provided by law.