Canon law was hostile to Jews in wording, but the popes also refused to accept popular violence against Jews. The following letter of Pope Gregory X (1271 -1276) incorporates material from earlier letters of Innocent III (1198-1216) and Innocent IV (1243-1254). Here Gregory X opposes the blood libel - the often repeated claim that Jews killed and ate Christian children. Pope Gregory's letter did not stop repeated accusations.
Gregory, bishop, servant of the servants of God, extends greetings and the apostolic benediction to the beloved sons in Christ, the faithful Christians, to those here now and to those in the future. Even as it is not allowed to the Jews in their assemblies presumptuously to undertake for themselves more than that which is permitted them by law, even so they ought not to suffer any disadvantage in those [privileges] which have been granted them. Although they prefer to persist in their stubbornness rather than to recognize the words of their prophets and the mysteries of the Scriptures, and thus to arrive at a knowledge of Christian faith and salvation; nevertheless, inasmuch as they have made an appeal for our protection and help, we therefore admit their petition and offer them the shield of our protection through the clemency of Christian piety. In so doing we follow in the footsteps of our predecessors of blessed memory, the popes of Rome Calixtus, Eugene, Alexander, Clement, Celestine, Innocent, and Honorius....
Inasmuch as thejews are not able to bear witness against the Christians, we decree furthermore that the testimony of Christians against Jews shall not be valid unless there is among these Christians some Jew who is there for the purpose of offering testimony.
Since it happens occasionally that some Christians lose their Christian children, the Jews are accused by their enemies of secretly carrying off and killing these same Christian children and of making sacrifices of the heart and blood of these very children. It happens, too, that the parents of these children or some other Christian enemies of these Jews, secretly hide these very children in order that they may be able to injure these Jews, and in order that they may be able to extort from them a certain amount of money by redeeming them from their straits.
And most falsely do these Christians claim that the Jews have secretly and furtively carried away these children and killed them, and that the Jews offer sacrifice from the heart and blood of these children, since their law in this matter precisely and expressly forbids Jews to sacrifice, eat, or drink the blood, or to eat the flesh of animals having claws. This has been demonstrated many times at our court by Jews converted to the Christian faith: nevertheless very many Jews are often seized and detained unjustly because of this. We decree, therefore, that Christians need not be obeyed against Jews in a case or situation of this type, and we order that Jews seized under such a silly pretext be freed from imprisonment, and that they shall not be arrested henceforth on such a miserable pretext, unless-which we do not believe-they be caught in the commission of the crime. We decree that no Christian shall stir up anything new against them, but that they should be maintained in that status and position in which they were in the time of our predecessors, from antiquity till now.
Sources: Tierney, Middle Ages, Vol 1, 259-60, no source given. Medieval Sourcebook