The brehons of ancient Ireland were wise individuals who memorised and applied the laws to settle disputes among members of an extended family. Some brehons were attached to clans, and were allotted a portion of land for their support. Others lived independently by their profession. They were recognised as a professional class apart from druids and bards, and became, by custom, to a large extent hereditary. The term ‘bard’ is associated with a Brehon Family of Poets, called Mac an Bháird(Son of the Bard). […]
The preparatory course of study extended over some twenty years. The Brehon laws were originally composed in poetic verse to aid memorisation. Brehons were liable for damages if their rulings were incorrect, illegal or unjust. When one brehon had adjudicated on a matter submitted to him, there could be no appeal to another brehon of the same rank; but there might be an appeal to a higher court, provided the appellant gave security. The ranking of a brithem was based on his skill, and on whether he knew all three components of law: traditional law, poetry, and (added later) canon law.
In Prechristian Medieval Ireland prior to the earliest written manuscript. Law was practised by hereditary judges known as bards or fili, who passed on information orally down the generations, they held the positions of Ollam to a provincial High king or rí.
Source: Brehon – Wikipedia