Once 23 individuals are qualified as grand jurors, the district judge will select a foreperson and a deputy foreperson from the 23. The normal term of a grand jury is 18 months, although the district court may provide it serve a shorter term. Certain special grand juries can have a term of three years. Grand juries normally meet at a time set by the United States Attorney. In most districts, they will meet monthly for one to four days depending on work load.
Most districts have more than one grand jury qualified at one time.
When the term of a grand jury expires, any unfinished work is normally transferred to the grand jury that takes its place. The grand jury will hear evidence of possible crimes committed within the district. It has the authority to issue subpoenas for individuals and records located anywhere in the United States or its territories. The grand jury's authority to investigate is extensive and only rarely will courts intervene in its investigations. The grand jury investigation may consist of hearing a single investigator report on the results of an investigation of a crime or it may involve months of testimony, extensive evidence, and numerous witnesses.