Irish society, up through the Iron Age, was based on the family unit. The family traditionally consisted of living parents and their children. The next larger unit came to be known as the Sept, which consisted of a closely related group of families such as the families of children of one set of parents and normally bore the same surname. The Clan (from clann meaning children) was the next larger unit and counted lineage from one ancestor. The Tuath (tribe) was generally considered the smallest political unit. It’s components were formed of several septs, houses or clans which likewise claimed descent from a common ancestor. The adoption of non-blood related individuals or groups into the Clan was a general practice. However, it required the formal approval or consent from the Clan members (Fine). Such a process resulted in a generous mixture of outside blood and the thus in many Clans the theory of one ancestor for all members became, in fact, just theory. Some leading families kept careful records of genealogy to prove unblemished lineage, but with the widespread practice of adoption, it would seem that some creative recording was likely.
The law recognised several general divisions or classes of society and set forth the rights, duties and privileges of all. The main (but not the only) consideration of rank was property. However, there were conditions in which an individual could pass from a lower rank to the next, provided they were honourable and industrious. Likewise, an individual could also pass to a lower rank for a variety of reasons, including illegal and/or dishonorable Kings. The various classes of society were as follows;
Ri (or rulers) were of several grades from that of the Tuatha to the Ard Ri of Ireland. In earlier times, the Ri may be of either gender and was elected into the position. If the Ri proved unworthy, for whatever reason, he or she could be voted out of office and another elected in their stead. Also, a temporary leader could be selected by the people for a specific purpose such as warfare. The mythological tale of Lugh is a good example. Lugh was chosen as temporary war leader of the Tuatha de Danann because of his excellence in the skills of warfare. The designation of a new ruler by heredity apparently did not come into being until between the 8th and 12th centuries. Even then it was not a universal practice. Consider the case of Diarmuid MacMurrough in the 12th century that brought the Norman Kings minions into Ireland to help him regain his lost crown. In addition to whatever land the RÌ held prior to election, additional land and property was provided to sustain the Brugh or hostel.
Nemedh (literally, privileged)
The Nemedh were the noble (uasal) class and were the upper level of society. Sometimes referred to as the Flaith. These were the intelligencia and the movers and shakers. These included the professionals such as historian, healer, law-keeper, stonemason, metal-smith, etc. They controlled the tribal land and determined allotment by size and quality. Outright “ownership” of land, as we know it today, was foreign to the Irish mentality and it was not until Norman occupation that true ownership came into being. Rather, land was held more or less “in trust” for the greater community. Several ranks of Uasal or Flaith existed and were generally in proportion to the amount of land and other properties held.
The Aire were rent paying freemen who owned property including cattle, and other movable goods. They were considered doernemed (non-privileged). Though they couldn’t hold land outright, they could “rent” land from a land-holder for certain fees which might include cattle or a percentage of harvested crops. There were several classes of Aire who were ranked according to their holdings. In some law texts, it appears that the Aire could become a Flaith and thus nemedh when sufficient goods were accumulated and he or she could prove that their ancestors had been land-holders. The Aire, like the RÌ and the Flaith, participated in the government of the clan or tribe.
The CÈile were free tenants. That is they held little of any property and rented land from the Flaith. Under the law, they could rise to the position of Aire when enough property had been accumulated. Also called FÈine and/or aithech, they formed the greater body of the populace and the farming class. The land they held was either tribal land or land held by a Flaith. The FÈine were the most important part of the community. They were the middle-class of their day and the larger portion of the clan. They were the foundation of the society and the ultimate source of law and authority. The FÈine included not only those working as farmers and herdsmen; it included trades and crafts. Of course some crafts such as precious metal workers were considered privileged beyond other less glamorous trades and could hold land in their own right and were considered Aire.
The non-free people of the tribe fell basically into three classes. They were the Bothach, Sencleithe and the Fuidir.
The Bothach and Sencleithe were herdsmen, laborers, horse-handlers, other unskilled laborers and squatters on wastelands. They were all poor and dependent on the good graces of the Nemedh for their survival. They did however have one valuable possession. They were part of the tribe and, though without most of its rights, they could claim to live within tribal territory and had the right to support themselves through their own labor.
The Fuidir were the lowest class within tribal territory. They were not members of the tribe and had no land rights. They were permitted to live within tribal territory only by the good graces of the RÌ. Any transgression could lead to immediate expulsion. Generally, the Fuidir was a stranger, often a refugee from another territory who, for whatever reason, had become a person without a tribe. The Fuidir were of two classes; saer-fudÌr and daer-fudÌr.
The saer-fudÌr were the higher. They were not free in the sense of the ceile, but they were-law-abiding and, coming into the district voluntarily could receive somewhat favorable terms when getting land on which to live and work. They had no voice in tribal government, but were not bonded as such. If they were successful in their endeavors, they could gain a status almost equal to the ceile. In legal matters though, they had no stature and could not give evidence against those of higher social rank.
This was the lowest social class in the tribe. It included captives taken in battle, escaped criminals, those convicted of crime and unable to make restitution and slaves. Yet in spite of their low state, the Law favored emancipation and it was possible for a daer-fudir to be elevated to saer-fuidir and in rare cases, even higher.
Source | Ancient Laws of Ireland: Uraicect Becc and Certain Other Selected Brehon Law Tracts, William Maunsell Hennessy