The function of the grand jury, which seems to have been instituted in England about the middle of the twelfth century, is to determine cause for criminal prosecution. Though instituted as a means of making the local community responsible for bringing its malefactors to justice, it has come to be regarded over the centuries as a safeguard against unwarranted prosecution and, as such, was incorporated in the Fifth Amendment to the United States Constitution, a provision that has not been made applicable to the states by the doctrine of selective incorporation; however, a correlative provision in the Texas Constitution of 1876 requires grand jury indictment for prosecution of a felony (see CRIMINAL LAW, ENGLISH LAW). The indictment is termed a "true bill" against a prisoner; a decision not to indict is termed a "no bill."
The district judge (or, in a county in which there are several district courts, the district judge designated for this purpose) appoints three to five citizens of the county to be jury commissioners. They serve either during the current term of court or during the succeeding term. These commissioners select fifteen to twenty persons from the citizens of the county to be summoned as grand jurors for the next term of court. Commissioners must, to the extent possible, select grand jurors who represent a broad cross-section of the population of the county, considering the factors of race, sex, and age. All potential jurors must meet certain other qualifications, including the ability to read and write. When twelve qualified jurors are found to be present, the court impanels them as a grand jury, with one juror appointed foreman. Before the grand jury has been impaneled, however, any person may challenge the entire jury or anyone presented as a grand juror. The term of the grand jury is the same as that of the district court that organized it, with some provision for extension at the judge's discretion.
The grand jury's investigation of any matter may be initiated by the court, the district attorney, its own members, or any credible person. The grand jury may summon witnesses by subpoena and examine them under oath. On completion of an investigation the grand jury determines by vote whether or not an indictment should be presented to the court; nine votes are necessary for a decision to indict, and nine members also constitute a quorum. The grand jury may also make reports to the district court on conditions in the county or the misconduct of an individual.