These rolls record the essoins (allowable excuses for non-attendance in court) made in King's Bench from 1272 onwards.
The series is a broken one, and there is only one roll later in date than 1422. During the fourteenth century the rolls gradually get smaller in line with the decline of King's Bench's share of civil business initiated by writ. The recovery and then rapid growth of that share in the fifteenth and sixteenth centuries was based on litigation by bill, in which essoins were not allowed, so the number of essoins continued to go down.
Although they have sometimes been regarded as unimportant, and were were deliberately omitted from the published Curia Regis Rolls series, they have more recently been accorded greater significance. Without them it is impossible to follow the course of many actions relating to land or understand the law and procedure they involved, and for some cases that never reached pleading they are the only evidence that they were ever initiated.