[6] That same year, in one of his earliest acts as pope, he expanded the Inquisition powers already assigned to Konrad von Marburg to encompass the investigation of heresy throughout the whole of Germany.

His solution was in the manner of a true follower of Innocent III: he issued what in retrospect has been viewed as the magna carta of the university, assuming direct control by extending papal patronage: his bull allowed future suspension of lectures over a flexible range of provocations, from "monstrous injury or offense" to squabbles over "the right to assess the rents of lodgings".

Gregory's aim was to bring order and legality to the process of dealing with heresy, since there had been tendencies by mobs of townspeople to burn alleged heretics without much of a trial.

In the 1234 Decretals, he invested the doctrine of perpetua servitus iudaeorum – perpetual servitude of the Jews – with the force of canonical law.

Following a public disputation between Christians and Jewish theologians, this culminated in a mass burning of some 12,000 handwritten Talmudic manuscripts on 12 June 1242, in Paris.

Gregory was a supporter of the mendicant orders which he saw as an excellent means for counteracting by voluntary poverty the love of luxury and splendour which was possessing many ecclesiastics.

He appointed ten cardinals[11] and canonized Saints Elisabeth of Hungary, Dominic, Anthony of Padua, and Francis of Assisi, of whom he had been a personal friend and early patron.

[13] In 1232, Gregory IX asked the Livonian Brothers of the Sword to send troops to protect Finland, whose semi-pagan people were fighting against the Novgorod Republic in the Finnish-Novgorodian wars;[14] however, there is no known information if any ever arrived to assist.

Gregory IX began his pontificate by suspending the Holy Roman Emperor Frederick II, for dilatoriness in carrying out the promised Sixth Crusade.

[1] In June 1229, Frederick II returned from the Holy Land, routed the papal army which Gregory IX had sent to invade Sicily, and made new overtures of peace to the pope.

Eberhard II von Truchsees, Prince-Archbishop of Salzburg, in 1241 at the Council of Regensburg declared that Gregory IX was "that man of perdition, whom they call Antichrist, who in his extravagant boasting says, 'I am God, I cannot err'.

The pope died before events could reach their climax; it was his successor, Innocent IV, who in 1245 declared a crusade that would finish the Hohenstaufen threat.