The law-code of the first Christian king of Kent, Æthelberht (died 616), is both the first piece of English law and the earliest datable work composed in English. It survives in a single manuscript as part of a compilation of laws and documents in Latin and Old English made at Rochester five hundred years after Æthelberht’s death, during the episcopate of Bishop Ernulf (reigned 1115–1124).

Called Textus Roffensis (‘The Rochester Book’), the manuscript demonstrates the importance of ancient English precedent to the Norman conquerors of England. Its contents range in date from the early 7th century to the coronation charter of King Henry I (reigned 1100–1135).

It preserves the only manuscript copy of many texts written in English, including three Kentish law-codes from before 725, records of serfs, and two items from the 10th century: the will of a layman, Byrhtric, and his wife, Ælfswith, and an English account of a property dispute precipitated by the theft of a title-deed.

Bede, in his Ecclesiastical History, stated that King Æthelberht had made a law-code in the manner of the Romans, which was written in English. This is usually interpreted to mean that Æthelberht, to whom Pope Gregory had held up the model of the Emperor Constantine (reigned 306–337), codified existing customary law to display his new identity as a Christian monarch.

In the kingdoms of early England, uniquely in post-Roman Western Europe, law was not committed to writing in Latin, but in the vernacular (Old English).