A grand jury is formed only in criminal cases. The purpose of the grand jury is not to determine whether a defendant is guilty or not. This group of usually 23 people meets to determine whether persons suspected by police as responsible for a crime should be indicted, allowing them to be brought to trial before a regular jury consisting of six to twelve persons. Grand juries are required by the Fifth Amendment of the U.S. Constitution which says a person suspected of a crime must be indicted before he is tried. This action is considered a safegurard against prosecuting a person without any legitimate reason.