Sui generis
Sui generis (; ) is a Latin phrase that means "of its (his, her, their) own kind; in a class by itself; unique."
Status in Roman legal system
"Status familiae" is the legal status of an individual in the family. The pater familias had the authority in the family (patria potestas), and everyone was subjected to him based on adgnatio (kinship only from father's side). This had an impact in private law. There is a distinction between alieni iuris (persons under patria potestas) and sui iuris (persons autonomous of patria potestas, who could only be the pater familias himself).
Filius familias had ius suffragii and ius honorum, but in the area of private law he was restricted because of patria potestas.