Persecution of Jews in the Roman and Byzantine Empires

Constantine I
Under the rule of Constantine I, the first Christian Roman Emperor, Jewish people were forbidden to perform the rite of circumcision on slaves or to own Christian slaves, and the death penalty was imposed on those that embraced Judaism and Jews versed in the Law who aided them. He issued a law that forbade marriages between Jews and Christians and imposed the death penalty on Jewish people who should break this law. Constantine's Edict of Milan in the 4th century caused Jews to lose many rights and were no longer permitted to live in Jerusalem or to proselytize.

Council of Nicaea
The Council of Nicaea was convened by Constantine in 325 and mandated the separation of the celebration of Easter from the Jewish calendar. Constantine on the results of the Council of Nicaea: “ ... It was declared to be particularly unworthy for this, the holiest of all festivals, to follow the custom [the calculation] of the Jews, who had soiled their hands with the most fearful of crimes, and whose minds were blinded. In rejecting their custom, we may transmit to our descendants the legitimate mode of celebrating Easter, which we have observed from the time of the Savior’s Passion to the present day [according to the day of the week]. We ought not, therefore, to have anything in common with the Jews, for the Savior has shown us another way; our worship follows a more legitimate and more convenient course (the order of the days of the week); and consequently, in unanimously adopting this mode, we desire, dearest brethren, to separate ourselves from the detestable company of the Jews, for it is truly shameful for us to hear them boast that without their direction we could not keep this feast. How can they be in the right, they who, after the death of the Savior, have no longer been led by reason but by wild violence, as their delusion may urge them? They do not possess the truth in this Easter question; for, in their blindness and repugnance to all improvements, they frequently celebrate two passovers in the same year. We could not imitate those who are openly in error. How, then, could we follow these Jews, who are most certainly blinded by error? for to celebrate the passover twice in one year is totally inadmissible. But even if this were not so, it would still be your duty not to tarnish your soul by communications with such wicked people [the Jews]. ...”

Constantius II
Constantius II was a Christian Roman Emperor during the 4th century and was the son of Constantine. He created laws that were beneficial to the Christian clergy and limited the rights of the Jews.

Destruction of the Callinicum synagogue
During 388, a Christian mob led by a bishop looted and burnt down a synagogue in Callinicum. Ambrose defended the bishop responsible and the Emperor did not punish him.

Leo III
Byzantine Emperor Leo III, in 722, outlawed Judaism and forced Jews to convert to Christianity.

John III Ducas Vatatzes
In 1253, Emperor of Nicaea, John III Ducas Vatatzes, committed legal persecution of the Jews and ordered that the Jews within the Empire of Nicaea to convert to Christianity.