Subject: Re: Lindsey, you got some 'splaining to do
Of course, that invites the question, why bother with a Grand Jury, if there is nothing to investigate, but only a rubber stamp to be applied to the prosecutor's presentation?

There's a short and a long answer. Short answer - it's required under the Constitution. All federal felony indictments have to go through a grand jury. Many state indictments also have to be issued by a grand jury. The prosecutors don't have the option to just issue an indictment on their own, even for the strongest cases.

Long answer - the grand jury historically served the important purpose of serving as a check against the rather immense power of the state in choosing whether to prosecute someone. The Founders recognize that the power to even begin a criminal case was really significant. So in the same way they required that a jury of one's peers be necessary in order to convict someone, they required that a jury sign off on the indictment phase as well. This was intended to be a material check by the People against the power of the State.

In practice, that check has been eroded over time. Citizens are generally inclined to give prosecutors a lot of deference and trust, moreso than during the immediate post-colonial days. That's largely because the nature of prosecutors has changed. We switched from appointed to elected prosecutors in most states during the mid-1800's, which created additional checks for the People on prosecutorial power. The development of the professional and apolitical prosecutor's office has also materially reduced concern about abuse of this power. There's now an enormous cultural presumption among the citizenry that when the prosecutor is presenting a case for an indictment, they've got a reason for doing it.

Grand juries still serve as a check against that power from time to time. The "sandwich assault" case got rejected by the grand jury it was presented to, and even in the Comey prosecution the grand jury rejected one of the charges. So it's not 100% a rubber stamp. And obviously, if the public starts to perceive that prosecutors are bringing cases for reasons other than a professional assessment that a probable crime has been committed by the suspect, we may start to see more charges rejected.