According to Annabelle Melville, biographer and president of the Catholic Historical Society of America, John Carroll was born in Upper Marlboro on January 8, 1735, at a time in which Maryland Catholics were conspicuously discriminated against. He was educated at St. Omer's in French Flanders. In 1753, Carroll entered the Jesuit Novitiate, later passing on to the Scholasticate in Liege. He returned to Maryland in mid-1774 and immediately sensed the discontent among Catholic merchants, so he joined the Continental Congress in Philadelphia. His presence helped gain assurances that Catholics would not be the victims of discrimination once independence was achieved. Catholics would not know religious freedom until after the American Revolution. Their support for the Revolution won them the right to a fair consideration from their fellow countrymen.
Before the American Revolutionary War, the colonies had been under the jurisdiction of the Bishop of London. With the Jesuits in Europe dissolved by the Papal Bull of Pope Clement XIV, Father Carroll found that he had no religious superior or affiliation. In June 1783, Father Carroll called a meeting of priests to be held at White Marsh, the former Jesuit residence. The group sent a message to Rome, requesting Father Lewis, the English delegate in the colonies, be appointed Superior with the power to bless chalices, holy oils and altar stones, and be authorized to administer Confirmation. The Papal nuncio in France consulted with Benjamin Franklin. Although a critic of Catholics, Franklin spoke highly of his friend John Carroll and favored an American Superior. Rome was apprehensive about Lewis' old age and influenced somewhat by Benjamin Franklin. In 1784 Rome appointed John Carroll Superior and Apostolic Prefect of the mission of the new republic of the United States of North America.
Upon receiving news of his appointment. Father Carroll sought to establish an educational institution in the new republic so that men would no longer have to travel to Europe in order to receive a Catholic education, helping to establish the Georgetown College. Nevertheless, it was becoming more and more difficult to grapple with the limitations of the Superior's powers. The ordination of new priests would have to take place in Canada or Europe. Father Carroll suggested to Rome that the American clergy nominate one of their own as Bishop. Rome agreed and an election was held at White Marsh on May 18, 1789.
It was John Carroll who was to become the "American Pacificus" in the struggle for religious equity and fair play. Charles Carroll of Carrollton and Daniel Carroll were to join in this struggle also. It was their combined influence that contributed more to the recognition of the principle of religious liberty, in the First Amendment to the Constitution of the United States, than any other factor.