Grand jury proceedings are conducted in secret, and the defense does not have an opportunity to present witnesses, cross-examine the prosecutor’s witnesses, or present evidence that rebuts the prosecutor’s theory of the case.  Jury trials, on the other hand, are public.  More importantly, jurors may hear from the defense, allowing them to make an informed decision.

 

A grand jury will be assembled for a term varying from a few weeks to a few months.  During this time the grand jury may hear about a specific investigation or may hear evidence from dozens of cases.  A trial jury will only hear evidence pertaining to one defendant.

 

The most important difference between the two is that a grand jury decides if someone should be charged, but a trial jury decides if someone is guilty.  For this, a grand jury only needs probable cause to return an indictment.  On the other hand, a trial jury must have proof beyond a reasonable doubt to return a guilty verdict.  This means that the standard is MUCH higher for a trial jury.  Jokes such as, “A grand jury will indict a ham sandwich” are made in response to the low amount of evidence a grand jury needs to return an indictment.