Lex Frisionum (the "Law of the Frisians", or more freely the "Frisian Law") was recorded in Latin during the reign of Charlemagne, after the year 785, when the Frankish conquest of Frisia was completed by the final defeat of the Saxon rebel leader Widukind.
The Frisians were divided into four legal classes, to whom the law, or those transgressions of it that incurred set fines, applied.
On numismatic grounds based on the amounts of fines (compositio) and wergeld, the laws from the Lex Frisionum date from the first half of the 7th century at the latest.
In that year, the scholar Joannis Basilius Herold made a compilation of all Germanic laws from the time of Charlemagne, Originum ac Germanicarum Antiquitatum Libri..., printed by Heinrich Petri of Basel.
Among them was printed the Lex Frisionum, but from what source, or how corrupted was Herold's text, is unknown; the title-page of his edition indicates that the material was drawn from the library (now dispersed) of the monastery of Fulda.