Freemasonry had developed in England in the seventeenth century, but after 1715 had split into Jacobite and Hanoverian lodges. The lodge in Rome was Jacobite (pro Stuart) and mainly Catholic, but admitted Protestants, while that in Florence was Protestant Hanoverian but also admitted Catholics and atheists who supported the Whig position. As Clement was from Florence, he did not view a prominent Protestant fraternity in his hometown favorably.
James Francis Edward Stuart was living as James III of England in Rome where he conducted a Jacobean court in exile. In 1737 he learned that Hanoverian Freemasons had recruited so many French Catholics that they had taken control of the Grande Loge de France from the Jacobites. He asked Clement XII to issue a papal bull condemning Hanoverian Freemasonry in the Catholic countries of Europe.
At the same time, Cardinal André-Hercule de Fleury was chief minister of Louis XV of France. Fleury was focused on maintaining peace with Britain. Jacobite sympathizers in France had formed a secret lodge of Freemasons; their attempts to influence Fleury to support the Stuart faction led instead to raids on their premises, and Fleury urged Pope Clement XII to issue a bull that forbade all Roman Catholics to become Freemasons under threat of excommunication.