How does a grand jury compare to a petit jury? O A grand jury determines if sufficient evidence exists to proceed to trial, while a petit jury determines guilt or innocence. A grand jury requires the participation of the defendant, while a petit jury often works only with the prosecutor. A grand jury is made up of trained legal experts, while a petit jury is composed of average citizens. A grand jury involves fewer people than a petit jury. O A grand jury is used in misdemeanor cases, and a petit jury is used in felony cases