How do federal grand juries work?

Today’s media is filled with references to grand juries, especially the grand juries that are hearing evidence presented by special counsel, Robert Mueller. Even with all this news coverage, few Massachusetts residents outside of the legal profession understand the function of grand juries.

Grand juries are used in federal criminal cases to decide if available evidence shows “probable cause” to believe that a crime has been committed. The Fifth Amendment states, “No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury.” Thus, a grand jury indictment is a necessary starting point for a federal criminal prosecution.

Grand juries are convened by federal prosecutors, who want to determine if enough evidence exists to support a criminal indictment. Grand juries are mostly used in cases involving serious federal crimes, such as murder or widespread financial fraud.

The prosecutor asks the federal court administrator in the district in question to empanel a grand jury comprising 12 to 23 members to hear evidence in the case. The grand jury will meet at regular intervals during their term of 18 months.

Once the grand jury is seated, the prosecutor will begin presenting evidence. No judge is present, and the witnesses are not allowed to have attorneys in the court room. The prosecutor will also explain the law to the jurors.

All grand jury sessions are confidential to encourage candor by the witnesses. After the prosecutor has presented all of the evidence, the jurors will vote on whether to return a finding that the evidence warrants indicting one or more persons on federal criminal charges.

A person who receives a summons to appear before a grand jury is not necessarily a suspect in the crime under consideration. Nevertheless, the advice of an experienced criminal defense attorney may help a person avoid making mistakes that could trigger an indictment.