A grand jury is a collection of individuals used to determine whether or not there is enough evidence to take a case to trial. For example: If you were arrested for a drug crime, a grand jury might be used to figure out whether or not the prosecution has a legitimate case against you. The grand jury will base its determination on witness testimony, documents, and other available evidence. At the end of the proceedings, the jury will decide whether or not the case will actually go to trial. If there is not enough evidence to conduct a trial, your case will not move forward. Grand juries are typically reserved for high-level felonies and federal crimes.