in law, body of persons selected to inquire into crimes committed within a certain jurisdiction. It usually comprises a greater number than the trial, or petit (also, petty) jury, having since early common law days had between 12 and 23 members. In the United States, federal grand juries have between 16 and 23 jurors. The grand jury receives complaints and accusations in criminal cases, hears evidence adduced by the state, and approves an indictment when satisfied that there is enough evidence against the accused to warrant a trial. It was not until the 17th cent. that the grand jury acquired its modern functions as a check on the discretion of prosecutors and a way of preventing unjustified and politically motivated prosecutions. Grand juries have investigative functions as well, and are sometimes impaneled to issue reports on, e.g., suspected official wrongdoing. The rules governing grand jury proceedings are very different from those governing trials by (petit) jury. The public is…