The Oath More Judaico or Jewish Oath was a special form of oath, rooted in antisemitism and accompanied by certain ceremonies and often intentionally humiliating, painful or dangerous, that Jews were required to take in European courts of law until the 20th century. More Judaico is Latin for "on/by the Jewish custom." The question of the trustworthiness of the Jewish oath was intimately connected with the meaning that Christian authorities assigned to the Kol Nidre prayer, recited by Jews on Yom Kippur, and the whole of the legislation regarding the oath was characteristic of the attitude of medieval states toward their Jewish subjects. The identification of Church and State seemed to render it necessary to have a different formula for those outside the state church.
Historical development
The disability imposed on a Jew engaged in legal contention with a Christian dates back to Byzantine emperorJustinian I, who declared that neither Jews nor heretics should be admitted as witnesses against Christians; secular courts, however, did not recognize this disability. Thus, in the safe conducts issued by the Carolingian kings in the 9th century, Jews and Christians were treated as equals, and consequently the testimony of the former, whether given under oath or not, was as admissible as the latter. This was distinctly stated in the charter granted by Holy Roman Emperor Henry IV to the Jews of Speyer in 1090. The law of DukeFrederick II of Austria, which served as a model for much other legislation on the Jews, merely required a Jew to swear "super Rodal". Similar laws existed in England, Portugal, and Hungary; Hungary waived the requirement to swear on the Torah in trivial cases. There were, however, some older laws that prescribed certain practices intended to mock Jews in court. These examples illustrated the kinds of humiliating rituals that accompanied the taking of the oath:
Byzantine Empire, 10th century: the Jew would wear a girdle of thorns around his loins, stand in water, and swear by "Barase Baraa", so that if he spoke untruth, he would be swallowed by the earth just like Dathan and Abiram in Numbers 16:1–27.
Arles : a wreath of thorns would be hung on the swearer's neck, others would grovel at his knees, and a thorn branch five ells in length would be pulled "between his loins" while he swore and called down upon himself all the curses of the Torah.
Swabia : the Jew would stand on the hide of a sow or a bloody lamb.
Silesia : the Jew would stand on a three-legged stool and have to pay a fine each time he fell, finally losing his case if he fell four times.
Dortmund: the Jew would be fined each time he halted in repeating the oath.
Vrbové, Hungary : the Jew would stand barefooted and swear with his face turned to the east, holding the Pentateuch in his hand.
Breslau : the Jew would stand bareheaded and pronounce the name of Yahweh.