Lex animata is a 12th century Latin translation of the Greco-Roman concept νόμος ἔμψυχος, nómos émpsychos, which equates to the "living law".
Originating in Hellenistic philosophy and repurposed by Themistius in the 4th century, the identification of the Roman sovereign as nomos empsychos was established in law by the emperor Justinian I in his Novellae Constitutiones, and introduced into European civil law through the discovery of The Authenticum by the medieval glossators in Bologna.
It would be a concept that would influence medieval ideas and shape early modern political thought about the state.