Gaelic law was originally passed down orally, but was written down in Old Irish during the period 600–900 AD. This collection of oral and written laws is known as the "Fénechas" or, in English, as the Brehon Law(s). The brehons (Old Irish: "brithem", plural "brithemain") were the jurists in Gaelic Ireland. Becoming a brehon took many years of training and the office was, or became, largely hereditary. Most legal cases were contested privately between opposing parties, with the brehons acting as arbitrators.