Jeanne Campbell, age 13, of Edison, N.J., for her question:

WHY ARE THERE 12 PEOPLE ON A JURY?

 Tradition has determined that many juries are made up with 12 members. There is no rule, however, that every jury have this number.  

In the United States, federal grand juries have from 16 to 23 members. The Constitution requires an indictment by a grand jury before trial for most federal crimes.

A coroner's jury inquires, or makes an inquest, into the causes of death in cases where there is doubt. This jury is usually made up of six members. In some states, the coroner's jury system has been abandoned and its functions are handled by a medical examiner.

A petit, or petty jury, has fewer members than a grand jury. Most federal and state petit juries have 12 members although some federal courts use six member juries in civil cases.