Sui generis
In sociology, the "sui generis" is what has been externalized, then internalized in the overall public and becomes a part of society that simply exists in its construct. It is not something that is not thought to have been created, because it is imbedded in everyone's way of thinking and being. Instances include the idea of love, or going to school, or clothing belonging to a specific gender. These examples are "sui generis" for they simply exist in society and are widely accepted without thoughts of where they come from or how they were created.
Sui iuris
In civil law, the phrase sui juris indicates legal competence — the capacity to manage one's own affairs (Black's Law Dictionary, Oxford English Dictionary) — as opposed to alieni juris, which means someone under the control of another (such as a child or mentally incapable person might be). It also indicates an entity capable of suing and/or being sued in a legal proceeding in their own name (in personam) without the need of an ad litem. (A court appointed representative, acting on behalf of a defendant, that is deemed to be incapable of representing themselves).