Did Justinian Actually Ban the "Deuterosis" from Yahudi Religious Use?

553 CE · Novella 146 §1.2 · Greek δευτέρωσις (deuterosis)

What the ancient record says

Yes, but with one of the most important source corrections in the collection. He explicitly prohibits δευτέρωσις (deuterosis), describing it as a secondary tradition outside what he regards as the sacred writings, characterizing it as human rather than prophetic.

Was deuterosis definitely the Mishnah? Unknown / disputed, older translations and many summaries identify it with the Mishnah, but that should not be presented as though the Greek word unquestionably means one specific surviving corpus; the safest source-first presentation: "Justinian prohibited what his law calls deuterosis," with the precise material requiring further historical identification.

Important because this project does not replace one inherited label with another and pretend the problem is solved, if the source says δευτέρωσις, we preserve deuterosis until the referent is established. He dismisses it as human invention, wanting the sacred writings themselves used rather than the secondary interpretations he condemns, so he intervened in interpretation too, beyond selecting the reading language.