Canon 69 of the Fourth Lateran Council decreed that Jews should be prevented from exerting any kind of political authority:
Since it is absurd that a blasphemer of Christ exercise authority over Christians, we on account of the boldness of transgressors renew in this general council what the Synod of Toledo wisely enacted in this matter, prohibiting Jews from being given preference in the matter of public offices, since in such capacity they are most troublesome to the Christians. But if anyone should commit such an office to them, let him, after previous warning, be restrained by such punishment as seems proper by the provincial synod which we command to be celebrated every year. The official, however, shall be denied the commercial and other intercourse of the Christians, till in the judgment of the bishop all that he acquired from the Christians from the time he assumed office be restored for the needs of the Christian poor, and the office that he irreverently assumed let him lose with shame. The same we extend also to pagans.
The Third Synod of Toledo in 589CE was organized by Bishop Leander of Seville who had worked to convert the Visigoths and King Reccared from Arianism to Roman Catholicism. It resulted in Visigothic Spain officially becoming part of the Roman Catholic Church. Its14th Canon forbade Jews to take Christian wives or concubines or slaves. Children from such a union were to be baptized. Jews were disqualified from any position that would give them authority over Christians. Christian slaves forced into following Jewish practices were to be freed.
Note that anyone who does hire or appoint a Jew to a position of authority where they make decisions that affect Christians is himself guilty and deserving of punishment. The Jew will be forced to return any material gain he had from Christians during the time in office, the value to be used for poor Christians.
(I apologize for "getting political," but I cannot help thinking of a current situation in the United States where immigrants are castigated for "taking jobs" from Americans, when the "crime"—if there is one—was committed by the business owners who, knowing the law, hired non-citizens in the first place. The workers suffer and the folk responsible are untouched.)
Denied the opportunity for many positions for which a Jew might have plenty of knowledge and skill—was this a reason why some Jews turned to lending money? If this was one profession that you were allowed and Christians did not generally go for, why not become a money-lender, which in some ways gave you more power over Christians than any public office? There were, of course, other options for employment, as in becoming a scribe as depicted in the illustration above, showing Jewish scribes from a 1283 Spanish work.
In the later Middle Ages, even as Jews were looked on with suspicion if not outright hostility, Jews were sometime valued for the skills they possessed. It was not unknown for the wealthy and nobility to retain Jews as physicians.
The final Canon of the Fourth Lateran, number 70, was concerned with apostasy. We'll wrap this up next time.