A predecessor of the present local government structure, the grand jury system was initially concerned with the administration of justice. Dating from medieval times the grand jury gradually evolved with its functions expanding to include dispensaries, county infirmaries, lunatic asylums, courthouses, schools, hospitals, public buildings, the county gaol, and the provision of roads and bridges. In addition, these bodies were in charge of the collection of the county cess, a local tax.
Grand juries mainly consisted of prominent local landowners, appointed by the sheriff.
In the early nineteenth century, provisions were made to make the grand juries more accountable to ratepayers. Baronial presentment sessions were established in 1819 and from 1833, these included representations from ratepayers. These sessions were held twice a year, in the Spring and Summer, in each barony, in addition to the county. The purpose of the spring and summer meetings was to pass presentments which consisted of printed lists of proposed and approved works to be undertaken which give a useful insight into infrastructural developments throughout Clare. Presentments which were not undertaken were know as 'undischarged queries'. Each volume lists the names of the justices, the high sheriff and the members of the grand jury.
Administrative duties of the Grand Jury ended with the introduction of the 1898 Local Government (Ireland) Act where the County Council, Urban and Rural District Councils were established (GJ/AP/41). This move greatly decreased the powers of local landowners, and instead introduced a system of elected county and city representatives for the first time.
Grand jury archives are considered to be the oldest archives of the local authorities and provide a rich source of information in terms of society, economics, culture and genealogy.