This regulation was formulated by the Kamakura bakufu, because the bakufu was worried about rivalries between the gokenin serving it, if one were appointed to Joshi while another was appointed to the post of Jito, which often corresponded to the lower ranks such as Geshi and Chushi, in order to control a Shoen manor.
これは鎌倉幕府によって正式に補任されて荘園を支配した地頭は荘官としては下司もしくは中司に相当する場合が多く、幕府に仕える御家人が上司となって幕府が補任した同じ御家人である地頭との間に上下関係が発生することを危惧したための規定である。