Grand juries are similar to regular trial juries (technically called “petit juries”) in that they are made up of randomly selected individuals who listen to evidence. However, there are some important differences between the two types of juries.
Burden of proof. Petit juries decide whether defendants are guilty beyond a reasonable doubt. Grand juries decide whether probable cause exists to believe suspects guilty and issue indictments (that is, to charge suspects with crimes).
Secret v. public. Grand juries meet in secret proceedings. Petit juries serve in public trials.
Evidence. An indictment may be based on evidence that has been illegally obtained and which must be kept out of trial. (United States v. Calandra, U.S. Supreme Court 1974.)
Length of service. Petit jurors usually serve for a short period, as little as ten days unless they serve on a longer trial. Grand jurors serve for longer periods that typically coincide with a term of court, often six to 18 months.
Size. Grand juries have 15–23 people, 16–23 in federal courts. (See Federal Rule of Criminal Procedure 6(a).) By contrast, a petit jury usually consists of six to 12 people.
Votes. Petit juries generally have to be unanimous to convict a defendant (there are some exceptions for misdemeanor crimes). Grand juries need not be unanimous to indict. In the federal system, for example, an indictment may be returned if 12 or more jurors agree to indict. (Federal Rule of Criminal Procedure 6(f).)
A prosecutor presents a bill (the charges) to the grand jury and introduces evidence—usually the minimum necessary, in the prosecutor’s opinion, to secure an indictment. The proceedings are secret and are held without the suspect or his lawyer present. The prosecutor may call a suspect or other witnesses to testify. (Any witnesses who think that they might be a target of investigation have a right not to answer questions.)
Indicted suspects can sometimes later obtain transcripts of grand jury proceedings, a big reason why prosecutors like to present as little evidence as possible.
If the grand jury decides to indict, it returns what is called a “true bill.” If not, the grand jury returns a “no bill.” However, the prosecutor may eventually file charges even after a grand jury returns a no bill. Prosecutors can return to the same grand jury with more evidence, present the same evidence to a second grand jury, or (in jurisdictions that give prosecutors a choice) bypass the grand jury altogether and file a criminal complaint.
This article was excerpted from The Criminal Law Handbook, by Paul Bergman, J.D., and Sara J. Berman, J.D.