The three pillars of Pre-Reformation Uruki law were the Family, Survival and the Oath.
The Uruki Family was sovereign. No one outside a Family had authority to interfere in the internal affairs of a family, and thus no laws about private behavior were ever created. Even a clan chieftain could not directly intervene in an internal family issue; though custom and respect for the clan gave him authority to hear cases if brought before him by the family. Of course, this limit to the power of the chieftain did not prevent him from banishing a family from the clan if it looked like it was necessary for the good of the clan.
Survival is the second pillar of Uruki law. Because life on the Great Central Plain was so difficult, capital punishment was never practiced; instead a system of fines was created to recompense victims (or their families, in the case of murder) call weregeld. This prevented blood-feuds and honor killings, which might have destroyed entire families. In addition, a high rate of stillbirths among the Uruki meant that women were expected to have as many children as possible; while still performing their duties in the profession of arms.
The third pillar of Uruki society was the Oath, which led both to a structured hierarchy and to the requirement that the all persons were skilled with arms, first and foremost. (This, of course, had an adverse affect on survival, because no one with any ambition would spend any more than a few hours a day on anything like farming, herding or weaving.)
The High King was the chief steward of the Uruki, and was responsible for all common property (lands, herds, etc.), which he then granted to Kings, Clans and Families for their use and management. He had the authority to change these grants as necessary for the good of the Uruki people. This power flowed downward such that kings had similar powers within their kingdoms, and clan chieftains within their clans.
One other effect of the three pillars of Uruki Law was the idea that in order to be an effective steward of the Army of the King Above, the high king and the kings had to be blemish free. Prior to accepting the crown, a newly elected king was inspected by a member of the Ran (doctor/midwife) and a lawspeaker, who verified his physical health and wholeness. Any major health problem or accident could disqualify one for the crown, and this led many people to spend as much time training for unarmed combat as with weapons.