Written by Avvo Staff

How does a jury work in a criminal case?

What to know about jury trials

When on trial in criminal court, you are likely to face a jury of peers. The jury will consist of 6 to 12 people from the community selected to evaluate the evidence and decide if you are guilty or innocent. Jurors are asked to make an impartial decision, meaning they are not supposed to have prior information of or pre-existing biases about you or the charges.

Not every case gets a jury

Jury trials are required for federal criminal cases where the defendant faces at least 6 months in jail. State or local courts may require juries more often. Some jurisdictions require juries for all criminal cases.

If your case does not require a jury, a judge will decide whether you are guilty of the charges against you. Minors facing criminal charges in juvenile court do not have a right to a jury and typically have their cases decided by judges.

The jury selection process

Jury selection, also called voir dire, draws potential jurors from all registered voters in the jurisdiction handling the case. A jury on a criminal court case has between 6 and 12 members.

Both the prosecution and the defense will ask potential jurors about their opinions on matters relevant to the trial. Lawyers are permitted to dismiss jurors for several reasons:

  • Bias against their side of the case
  • Prior knowledge of the case
  • Previous experience with similar charges
  • Previous jury experience

Lawyers may also use a limited number of “peremptory strikes,” in which they can dismiss a prospective juror without giving a reason. The US Supreme Court has ruled that lawyers may not use peremptory strikes based solely on a juror’s race, gender, or ethnicity.

Jury duties

During the trial, the jury listens to, sees, and reads all of the evidence presented. Although jurors have historically not been allowed to ask questions during the trial, some jurisdictions now permit juror questions.

Some courts may allow jurors to take notes, but the majority of courts prohibit this practice. Jurors may not discuss the case with anyone else, even other jurors, until deliberation begins.


Before jury deliberation, the jury receives instructions on the law related to the case and the implications of guilty or not guilty verdicts. Jury instructions may also tell jurors how to deal with certain types of evidence or testimony presented during the trial.

Jury instructions also help jurors understand the standards they must reach to convict defendants. The evidence must show beyond a reasonable doubt that defendants committed the crime.

In most states, the jury instructions are a standardized set of guidelines, also called pattern jury instructions, with the name and circumstances of the case filled in. The judge or lawyers for both sides may be able to add additional instructions to cover issues specific to the case.

Outside influences

Jurors are not permitted to read, watch, or listen to outside news or discussion about the trial, such as newspaper, website, or TV coverage. They may not conduct their own research into the circumstances of the case or into the law.

In exceptional cases, if the jury does not reach an agreement at the end of the first day of deliberations, they may be required to stay in a hotel until the case is over, where their access to outside news and information is restricted.

Jurors are not allowed to accept money or other benefits from any parties in the trial or in exchange for their votes.


After closing arguments, jury deliberations begin. Using the instructions given by the judge, the jury evaluates the trial evidence.

The jurors discuss whether the evidence proves beyond a reasonable doubt that the defendant is guilty or not guilty of each of the charges. They may ask for clarification of law or evidence during the deliberations.

Reaching a verdict

In most criminal cases, the jury’s decision must be unanimous; Oregon and Louisiana are the only states where non-unanimous criminal verdicts are allowed, and even then there are some restrictions on how they may be used.

If the jurors cannot agree on a verdict, the jury is considered “hung” and the case is declared a mistrial. Mistrial cases may be tried again later with a different jury, or the prosecutor may decide not to bring the case again, in which case the charges are dropped and the defendant goes free.

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