You hear the term all the time, but is there really anything special about grand juries?

Not on the surface. Like a regular trial jury, a grand jury is selected and sworn in by a court, and are often, in fact, pulled from the same pool of people as trial jurors.

The job of a grand jury is a little different, though.

While a regular trial jury hears both sides of a criminal case and renders a verdict, the grand jury only hears the prosecution’s side of the case and decides only if there’s enough evidence to officially charge the defendant with a crime. Essentially, they act as a filter for criminal trials.

In grand jury hearings, there's no judge, no defense attorney and no defendant. The State's prosecutor simply puts a case before the jurors and attempts to show that the defendant should be indicted and go to trial. The defense is not permitted to attend the hearing, question the State's witnesses, or present witnesses or evidence of their own.

This system may seem a little skewed in favor of the prosecution, but grand juries don't just “rubber stamp” the cases brought before them. They often wind up not handing down indictments because the cases aren't strong enough to go to court. And just because the defense attorneys can't be there for the hearing doesn't mean they can't intercede. When the OJ Simpson case went to grand jury, for example, the defense claimed that no grand jury could make an impartial decision about the case after hearing so much about it in the media. The court agreed, granted the motion and, in lieu of another grand jury, held a week-long preliminary hearing where California Superior Court Judge Kathleen Kennedy-Powell eventually ruled that there was sufficient evidence to bring Simpson to trial.

There are some slight differences of procedure between trial juries and grand juries, too. Depending on the jurisdiction, a grand jury can have anywhere between six and 23 members. In many states, grand jurors can serve for up eighteen months and hear several different cases in that time.