For the last two hundred and fifty years assizes have been an almost exclusively judicial tribunal. Yet too much emphasis on assizes as a court of law conceals what was for much of this period its distinctive and most important function. For to Elizabethan and early-Stuart government the unique value of assizes lay not so much in its judicial contribution–though as a factor in preserving that precious commodity, the public peace, this should not be underestimated–but in its potential as a vehicle of executive control.

Contemporaries recognized that the executive contribution of judges going circuit was not confined to the exercise of interpretive powers in civil and criminal suits but extended beyond this to duties normally not associated with the judicial function. Successive Lord Keepers in delivering the Star Chamber charge groped for a telling metaphor to express the essence of an ‘extra-judicial’ authority which commanded respect by its very intangibility. Judges riding circuit were visitors, the king's mouth, his ears, the eyes of the kingdom.