The Presbyterian Church (U.S.A.) voted at its General Assembly on Thursday to change its constitution’s definition of marriage from “a man and a woman” to “two people,” and to allow its ministers to perform same-sex marriages where it is legal.

Both measures, passed by large majorities, are a reversal for a church that in 1991 and in 2008 barred its pastors from performing same-sex marriages, and that has held ecclesiastical trials for ministers who violated the ban and blessed gay couples.

The Presbyterian Church, a historic mainline Protestant denomination that spans a broad spectrum from liberal to conservative evangelicals, has been mired in the debate over homosexuality for about three decades. The General Assembly’s decision in 2010 to ordain openly gay ministers caused many congregations, including some of the largest, to depart.