The Grand Jury, the buffer between the citizenry and an overzealous government. Explanation of the origins, use and meaning of a Grand Jury. The Grand Jury, "We the People" are the buffer between a tyrannical government and we have the power to nullify any unscrupulous law. The power of the State and Federal legislators are completely dependent upon whether a Grand Jury made up of people like you and me, agrees to indict. Most powerful tool we have against a police state. You want to change things? Don't worry about who gets elected, the Grand Jury can make them all lamb ducks!