In the 1234 Decretals, he invested the doctrine of "perpetua servitus iudaeorum" – perpetual servitude of the Jews – with the force of canonical law. According to this, the followers of the Talmud would have to remain in a condition of political servitude until Judgment Day. The doctrine then found its way into the doctrine of "servitus camerae imperialis", or servitude immediately subject to the Emperor's authority, promulgated by Frederick II. The Jews were thus suppressed from having direct influence over the political process and the life of Christian states into the 19th century and the rise of liberalism. In 1234, Gregory issued the papal bull "Rachel suum videns" calling for a new crusade to the Holy Land, leading to the Crusade of 1239.