It wasn't the first of the Standing Order churches to split, but it sure made the biggest bang.
In Puritan New England, each town was organized around its church. The members of the church were those who made a confession of Christian faith, while members of the parish were those who lived in the town and paid the poll tax that supported the church, but hadn't had a religious experience of conversion in the church. Reflecting this two-tier arrangement, the minister was the spiritual leader of the church as well as the teacher of public morals to the townspeople. These were the Standing Order churches—church and parish in the same institution, with a religious leader and public preacher in the same person.
In Dedham, Massachusetts, a controversy about theology became an ecclesiastical, political, and legal battle—one of the first to challenge the Standing Order system. In 1818, the Dedham parish invited Alvin Lamson to be its candidate for the ministry. A majority of the church members, being orthodox, rejected Lamson's liberal views. They voted their refusal to have him as minister. By custom, the church members decided who the minister would be, but in Dedham, the parish—which was more liberal than the church membership—went ahead and called Lamson as the minister.
The church members weren't going to stand for that. So they left, taking the church records, the communion silver, and the financial assets with them. That's when Deacon Baker—of the liberal camp in the church membership—sued Deacon Fales—of the orthodox camp—for the return of all the church property. Fales and the church majority claimed that the assets were the property of the church, and since the majority of the church was leaving, the assets were theirs to take. Baker and the liberal church minority maintained that the assets belonged to the parish, and as the parish majority was staying put, they would like all their assets returned.
The liberal minority prevailed. A jury ruled that according to the law, the church was built and run at the parish's expense for the benefit of the whole parish, and the minister worked for the benefit of the whole parish. Therefore, the parish owned the assets, and what's more, the parish had the right to call the minister. Some cried "foul," noting that the presiding judge, Isaac Parker, was himself a Unitarian. But when all the appeals were finally over in 1821, the ruling stood.
The decision rocked the Standing Order churches, many of which had already started to come apart. In some towns, a liberal minority left to establish a new church. In others, an orthodox minority left to found a congregation of their own. The reverberations went on for decades, with a quarter of Massachusetts Standing Order Congregational churches becoming Unitarian within the next twenty years. Three of the churches chose to become neither Unitarian nor Congregational, but Universalist.