Brehon Law is a series of laws that governed Gaelic Ireland from the Mythic Era all the way until the fall of the Gaelic order in the 1600's. These laws were administered by people called Brehons, who traditionally were a kind of druid specialist, that focussed almost exclusively on the laws. The Brehons almost never wrote these laws down, and never did until after the arrival of Christianity. The Brehons would memorise the laws in poetic verse.
The Brehon Laws were memorised and recorded in tracts, the largest of which was the Senchus Már (Seanchas Mór in modern Irish). Sadly, we will not be providing you with much of substance here for the time being, but we are working on writing the laws down and making them into an official book which will be available for purchase when we finish it.