The detail
The Old Catholic movement has two roots. The first is Dutch. In the Netherlands, where Catholicism survived as a tolerated minority after the Reformation, a long conflict over Jansenism and over the rights of the Utrecht cathedral chapter led to the chapter's election of Cornelius Steenoven as archbishop of Utrecht in 1723 without papal approval. He was consecrated in 1724 by Dominique-Marie Varlet, a French missionary bishop, and Rome declared the act illicit. From then on the Church of Utrecht maintained its own line of bishops, considering itself Catholic but not under papal jurisdiction.
The second root is the First Vatican Council. On 18 July 1870 the constitution Pastor aeternus defined that the pope has full and immediate ordinary jurisdiction over the whole Church and that, when he speaks ex cathedra on faith or morals, he possesses the infallibility Christ willed for his Church. A significant minority of bishops had opposed defining it, but they left before the vote or later submitted. Among theologians, however, the historian Ignaz von Döllinger of Munich refused to accept the dogmas, arguing that they contradicted the history and practice of the early Church; he was excommunicated in 1871. Döllinger himself never formally joined the Old Catholic church.
Congresses of opponents met in Munich (1871) and Cologne (1872). In 1873 Joseph Hubert Reinkens was elected bishop for the German Old Catholics and consecrated by Hermann Heykamp, bishop of Deventer in the Utrecht church, which passed on its episcopal succession. A Christian Catholic Church formed in Switzerland (with its first bishop, Eduard Herzog, in 1876), and smaller communities in Austria and elsewhere. In 1889 the bishops signed the Declaration of Utrecht, forming the Union of Utrecht: they appealed to Vincent of Lérins' rule of faith "what has been believed everywhere, always and by all", accepted the seven ecumenical councils and the doctrinal decisions of the first millennium, and rejected the Vatican decrees and other later Roman definitions.
Over time Old Catholics introduced vernacular liturgy, abolished compulsory clerical celibacy and, in some churches, adopted other changes. They entered full communion with the Church of England through the Bonn Agreement (1931). Their decision to ordain women (the German church from 1996) led the Polish National Catholic Church, which had joined the Union in 1907, to leave it in 2003. Theological dialogue with the Orthodox produced substantial agreement texts (1975–1987), though not communion.
How each side tells it: Old Catholics see themselves as holding to the faith of the undivided Church and to the older Catholic understanding of the papacy, which they say was altered in 1870. The Catholic Church considers that Vatican I defined what had always been believed and that the Old Catholics separated themselves from communion, while generally recognising the validity of their orders and sacraments. Historians note that the 1870 debate was intertwined with liberalism, nationalism and the Kulturkampf in Germany, where the government initially supported the Old Catholics.