Understanding the Difference Between a Trial Jury and a Grand Jury

There is a lot of confusion and misunderstanding out there about the difference between a grand jury and a trial jury, and their roles in a criminal case. It’s important to understand how each one works and how they differ from one another. Let’s examine some of the main differences between a grand jury and a trial jury.


A grand jury is a body of individuals summoned from the community to determine whether or not an indictment should be issued which formally charges a person or persons with a crime. The work of the grand jury is done in secrecy, and is not open to the public. This is so that the target of a grand jury investigation will not know that it is being conducted, and try to flee or somehow influence the proceedings to their benefit. Typically, a grand jury is empaneled for a specific term of months, and hears hundreds of cases.

A trial jury (or petit jury) is also comprised of individuals from the community, and is charged with the responsibility of hearing the evidence in a trial and determining if the defendant is guilty or not guilty. This is the type of jury you see in a news report, or on a television show. Their work is done in a courtroom which is open to the public. Unlike a grand jury though, a trial jury only hears one case.


The most significant difference between a trial jury and a grand jury is the size. Both juries consist of every-day American citizens who have been called for jury duty, but a trial jury will consist of 6-12 jurors, while a grand jury will range from 16-23 jurors.


A grand jury hearing is a pre-trial proceeding, while a trial jury of course hears a trial. In both a grand jury and a trial jury, one member is chosen to be the foreperson. They are the ones who maintain order and control deliberations, much like the leader of any meeting. While both types of juries hear evidence, the manner in which it is presented to them is significantly different.

In a grand jury proceeding, the only persons who are permitted in the room are the members of the grand jury, a prosecutor who presents the case, the witness who is testifying and a court reporter who is recording the proceedings. The prosecutor presents the witness testimony, and any other evidence which she selectively chooses. There is no requirement that the prosecutor present all of the evidence known to her, or even evidence which would tend to negate the guilt of the person being investigated.

Most significantly, the target of the grand jury and his attorney are not present to challenge the evidence, cross examine the witnesses or present exculpatory evidence. The members of the grand jury can however ask questions of the witness. Finally, there is no judge present to make rulings on whether or not a particular piece of evidence presented to the grand jury is properly admitted. Essentially, the prosecutor controls the proceedings, with the goal of having the grand jury return an indictment. If an indictment is returned, the individuals named as defendants are arrested, and proceed to the trial phase of the case.

In a formal trial of a criminal case, the defendant who is on trial is present at all times, as is his lawyer. The government is represented by the prosecutor, who must present her case in accord with the law and the rules of evidence. The judge controls the conduct of the trial, overseeing all procedural matters and making rulings based upon the rules of evidence. As we know, it is during the trial that the criminal defense attorney challenges the evidence, cross examines the witnesses and argues on behalf of his client. The trial jury has no input over the proceedings and usually does not get to ask questions. After all of the evidence is in, and the lawyers have presented closing arguments, the judge instructs the jury on the law which applies to the specific case, and they retire to deliberate. It is the role of the trial jury to determine if the defendant on trial is guilty or not guilty of the crimes charged.

Length of Time

Grand jury proceedings can last for months on end, but the jurors will only be required to be involved for several days each month. Conversely, a trial jury will have to be present for all formal trial proceedings, and though a trial may not last as long as a grand jury term, a trial jury will have to be there every day until they retire for deliberations and reach a verdict.

A trial jury’s verdict is final (appeals notwithstanding) and establishes the guilt or innocence of the defendant, whereas a grand jury’s decision does not establish a verdict and only serves as a starting point in the prosecution of a crime.

If you or a loved one are being investigated by a grand jury, have received a subpoena to testify or produce documents before a grand jury, or have been indicted and are facing trial, give us a call to help you make the right decisions and take back control of your life!

Law Offices of Barry M. Wax