Year Books.Hist. Books of cases anonymously and fairly regularly reported covering primarily the period from the reign of Edward I to the time of Henry VIII. • The title “Year Books” derives from their being grouped under the regnal years of the sovereigns in whose reigns the reported cases were cited. The reports were probably originally prepared by law teachers and students and later by professional reporters or scribes. — Also written Year-Books; year-books; yearbooks. — Also termed terms. Cf. ABBREVIATIO PLACITORUM.

“[F]rom 1300 there is a continuous stream of reports of arguments in the common Pleas. The reports were written in Anglo-French, the language of courtly speech. Their authorship is unknown, and they are referred to by the generic name ‘year-books’ …. If we have to account for their beginning, the most likely explanation is that they arose from a case-method of instruction in the law school which served the apprentices of the Bench before the emergence of the inns of court …. For the same reason, the contemporary value of the earliest reports lay not in their historical authenticity as precedents but in the ideas and suggestions which they contained …. Once the age of experiment was over, the reports settled into a more uniform and at times apparently single series …. The year-books did not end at any fixed date. What has usually been taken as their end is the result of two concurrent factors: the advent of printing, and the practice of identifying reports by the name of the author.” J.H. Baker, An Introduction to English Legal History 205–07 (3d ed. 1990).
[Blacks Law 8th]