Grand juries have historically served two functions: accusatory and protective. The accusatory function has roots in the English common law. The Founders’ motivation for adding this provision to the U.S. Constitution was principally to protect those accused of crimes from prosecutorial overreaching. Contemporary practice, however, limits the extent to which grand juries are capable of performing this second aspect of their traditional role.

A typical federal grand jury consists of twenty-three citizens drawn from the community. The jurors meet in a closed courtroom, with no judge, no accused, no press, and no lawyer except the prosecutor present. The prosecution presents evidence that a particular suspect committed a crime; the prosecutor is then excused, and the jurors deliberate and vote on whether there is enough evidence to justify the filing of criminal charges against this suspect and sending the case forward to trial. If a majority of jurors believe that there is sufficient evidence, the jurors return a “true bill,” which when signed by the prosecutor becomes the indictment: the formal criminal charge that the government must prove beyond a reasonable doubt at trial.

The evidence that is considered by the grand jurors may have been gathered by law enforcement, but also may have been gathered by the grand jury itself. Normally under the direction of the prosecutor, the grand jury may subpoena witnesses to come before them to testify, and those who refuse may be held in contempt. Although the subpoena power is a powerful investigative tool for the prosecutor, a witness may not be required to provide information that is protected by the Fifth Amendment privilege against self-incrimination or other privileges. The grand jury also may issues subpoenas duces tecum, requiring a witness or entity to produce documents and other tangible objects for review.

The most distinctive feature of federal grand juries is their secrecy. Even though a transcript is made of the proceedings, matters occurring before the grand jury may not be revealed by the jurors or by the government, on pain of contempt, subject to certain exceptions set forth in the Federal Rules of Criminal Procedure. This requirement is taken very seriously by the courts, and grand jury materials remain secret even after the case is finally resolved. Grand jury witnesses, however, are not subject to the secrecy requirement, and they are free to disclose information they learn to anyone they wish.

Grand juries originated in England, probably in the twelfth century, and began as an effort to increase the King’s power. Their original purpose was strictly accusatory—grand jurors were expected to bring to the proceedings any information or suspicions they had about their neighbors’ involvement in crimes. By the mid-seventeenth century, however, the jurors also assumed the responsibility to investigate and protect citizens against unfounded charges. This dual role of accuser and protector was the model that settlers brought with them to this country. The first grand-jury session was held in Virginia in 1625, and the practice soon spread to the other English colonies.

Prior to the American Revolution, the grand jury’s role as a shield took on increasing importance. The most famous such case involved John Peter Zenger, accused of seditious libel in 1734 for publishing material that was critical of the governor of New York. The evidence against Zenger was strong, but three grand juries refused to indict, impressing on colonists their power to frustrate the enforcement of unpopular laws. As the Revolution drew closer, royal prosecutors who tried to enforce English tax and import laws at times found themselves stymied by local grand juries, who at times refused to let even meritorious cases go forward to trial. These experiences, coupled with the writings of influential legal thinkers (particularly Sir William Blackstone, Henry Care, and John Adams), convinced the colonists of the need for grand-jury review as a restraint on government power. When there was no mention of grand juries in the original Constitution, the criticism was swift; so in December 1791, the Fifth Amendment to the Constitution, containing the Grand Jury Clause, was ratified.

The Supreme Court has not, however, given the Clause a robust interpretation. The Court has concluded, for example, that unlike nearly all of the other provisions of the Bill of Rights, the Grand Jury Requirement Clause is not “incorporated” against the states through the Due Process Clause of the Fourteenth Amendment. That is, the federal Constitution does not require that states use grand juries at all. If states do use grand juries, they are not required to follow the federal procedures. Hurtado v. California (1884). The result is that many states use grand juries sparingly, and, when they do, they follow significantly different procedures than is used in federal criminal cases. Given that states are still the primary enforcers of the criminal law, this interpretation severely limits the importance of this part of the Fifth Amendment.

The Supreme Court’s current interpretation of the Fifth Amendment also restricts the ability of a grand jury to serve as a significant shield against prosecutorial overreach. There are several reasons for this. First, the Court has greatly limited the ability of criminal suspects to challenge federal grand-jury procedures. Because the proceedings are secret, a suspect has no way of knowing if the evidence presented by the prosecution is complete or accurate. Even if a suspect can determine what evidence the jury hears, his ability to attack the indictment based on this information is small. Federal courts have not required prosecutors to disclose evidence to the grand jurors that is favorable to the accused. See United States v. Williams (1992). In addition, a suspect has no ability to challenge an indictment even if the jurors only considered evidence (such as hearsay) that would not be admissible in a later trial; “[a]n indictment returned by a legally constituted and unbiased grand jury,” the Court has said, “if valid on its face, is enough to call for a trial of the charge on the merits. The Fifth Amendment requires nothing more.” Costello v. United States (1956).

Second, criminal law enforcement has changed dramatically since the Bill of Rights was ratified. Prosecutors are now highly professional and specialized, and federal criminal laws have become more complex. One result of this change is that grand jurors lack the ability to decide whether the prosecutor has presented “enough” evidence to justify an indictment. The question that jurors are asked is ultimately a legal one concerning the sufficiency of the evidence, a question that is posed after the only lawyer in the room—the prosecutor—has recommended that the defendant be indicted. Because the prosecutor has complete control over the evidence the grand jurors hear, and because the jurors have no benchmark against which to measure that evidence, it is rare for jurors to second-guess a prosecutor’s recommendation to indict. Consequently, grand jurors agree with the prosecutor’s recommendation and return a true bill in nearly every case where they are asked to do so.

So despite the original purpose of the Fifth Amendment, most observers now agree that the grand jury has returned to its accusatory roots and is now used as an investigative tool that is much more of a benefit to the prosecutor than to criminal suspects. Perhaps as a consequence, suspects often waive the right to grand-jury review of their case; they may prefer to forgo the minimal protection that comes from this review and avoid the potential for a more searching investigation of their conduct.