Early Irish law, also called Brehon law, comprised the statutes which governed everyday life in Early Medieval Ireland. They were partially eclipsed by the Norman invasion of 1169, but underwent a resurgence from the 13th until the 17th centuries, over the majority of the island, survived into Early Modern Ireland in parallel with English law. Early Irish law was often, although not universally, referred to within the law texts as Fenechas, the law of the Feni or free men of Gaelic Ireland mixed with Christian influence and juristic innovation. These secular laws existed in parallel, and occasionally in conflict, with canon law throughout the early Christian period.
The laws were a civil rather than a criminal code, concerned with the payment of compensation for harm done and the regulation of property, inheritance and contracts; the concept of state-administered punishment for crime was foreign to Ireland's early jurists. They show Ireland in the early medieval period to have been a hierarchical society, taking great care to define social status, and the rights and duties that went with it, according to property, and the relationships between lords and their clients and serfs.
The secular legal texts of Ireland were edited by D. A. Binchy in his six-volume Corpus Iuris Hibernici. The oldest surviving law tracts date from the 8th century.
No single theory as to the origin of early Irish law is universally accepted. Early Irish law consisted of the accumulated decisions of the Brehons, or judges, guided entirely by an oral tradition. Some of these laws were recorded in text form by Christian clerics. The earliest theory to be recorded is contained in the Prologue to the Senchas Már. According to that text, after a difficult case involving St. Patrick, the Saint supervised the mixing of native Irish law and the law of the church. A representative of every group came and recited the law related to that group and they were written down and collected into the Senchas Már, excepting that any law that conflicted with church law was replaced. The story also tells how the law transitioned from the keeping of the poets, whose speech was "dark" and incomprehensible, to the keeping of each group who had an interest in it. The story is extremely dubious as, not only is it written many centuries after the events it depicts, but it also incorrectly dates the collection of the Senchas Már to the time of St. Patrick while scholars have been able to determine that it was collected during the 8th century, at least three centuries after the time of St. Patrick. Some of the ideas in the tale may be correct, and it has been suggested by modern historians that the Irish jurists were an offshoot from the poetic class that had preserved the laws.