How does a petit jury differ from a grand jury?

In the context of the legal system, petit juries and grand juries serve distinct roles in the administration of justice. The primary differences between them are their functions, their level of secrecy, and the standards of proof they apply.123

Key Differences

• Function: A grand jury is inquisitorial and accusatorial; its purpose is to examine evidence to determine if there is "probable cause" to believe a person has committed a crime and should be formally charged via an indictment. In contrast, a petit jury (or trial jury) is tasked with hearing evidence during a trial to determine the guilt or innocence of the accused.241
• Standard of Proof: A grand jury decides if there is sufficient evidence to warrant a trial, whereas a petit jury must determine if the defendant’s guilt has been proven "beyond a reasonable doubt".24
• Proceedings: Grand jury proceedings are typically secret and informal, and they generally do not include the defense attorney or the judge. Petit jury trials are public, formal proceedings conducted in a courtroom under the supervision of a judge.241
• Composition: A grand jury typically consists of 16 to 23 members, while a petit jury usually comprises 6 to 12 members.124