Bamberg, Dom, Detail from the

Fürstenportal Last Judgment Tympanum ca. 1200

 Justinian's Digest  1.1.9 Gaius 1 inst.  Omnes populi, qui legibus et moribus reguntur, partim suo proprio, partim communi omnium hominum iure utuntur.

(All peoples who are ruled by laws and long-standing custom partly use their own laws and partly the law that is common to all men.)

Dig.1.1.10pr. Ulpianus 1 reg. Iustitia est constans et perpetua voluntas ius suum cuique tribuendi (Justice is the constant and perpetual will of giving everyone their Ius).