“Juramentum Judaeorum” (Jewish Oath) [Present-day Italy; Lombard Kingdom] [Unconfirmed]
Commentary from other sources:
1) The earliest referral to the “Juramentum Judaeorum” (the Jewish Oath): the concept that no heretic could be believed in court against a Christian. Various methods were used to ensure that Jews would tell the truth. These included swearing on an opened Torah scroll while standing on a pig-skin or while wearing a belt of thorns, or even standing on a stool wearing a “Jews hat.” [The decree could have been issued by King of the Lombards Agilulf.]
Avraham, Yerachmiel Ben: All in the Name of Jesus: The Murder of Millions (2016)