With our understanding of the probable kin-based organization of the Nephites as we have seen throughout their history, we can make some assumptions of how these judges were selected.
The first piece of information we have is that the assembled themselves “together in bodies.” This doesn’t tell us too much, but it does clearly indicate that this was not a single gathering of all Nephites. If they were to assemble in smaller groups, the most logical grouping would be by kin. All people belonged to kin groups, and not all belonged to churches, so the kin groups would be more logical structures to use.
If they gathered together as kin, then the selection was from among their own kin. Each kin group would recommend a judge that came from their own kin. As a kinsman, he would particularly watch out for the interests of his kin against another judge who might favor his own kin. This selection of kin-based judges would provide some type of check among the judges. Since each might favor his own kin, each would also watch for that tendency in others, and hold it in check for the common good of all.
This general structural organization persisted through to Aztec times. In the more complete quotation noted above, we now concentrate on the kinship aspects of the leaders rather than their use of “the voice of the people:”
“Each district or calpulli in the capital had its own chief, the calpullec, who was elected for life, preferably from the same family, by the inhabitants, and confirmed by the emperor. He had a council of elders, the ueuetque who were probably the oldest and best-known heads of families, and ‘he never did anything without taking the opinion of the elders.” (Soustelle, Jacques. The Daily Life of the Aztecs. Stanford University Press. 1970, p. 40).
In the later Aztec example, it is precisely the kin group that creates the judge for that group. While this leader is not necessarily the same as the judges in the Aztec empire, the principle for the election of leaders on the basis of their kin affiliation is very much the same principle as that which would have been used among Mosiah’s people.