Peritus is the title given to Roman Catholic theologians who are present to give advice at an ecumenical council

Ecumenical council

An ecumenical council is a conference of ecclesiastical dignitaries and theological experts convened to discuss and settle matters of Church doctrine and practice....

. At the most recent council, the Second Vatican Council

Second Vatican Council

The Second Vatican Council addressed relations between the Roman Catholic Church and the modern world. It was the twenty-first Ecumenical Council of the Catholic Church and the second to be held at St. Peter's Basilica in the Vatican. It opened under Pope John XXIII on 11 October 1962 and closed...

, some periti (the plural form) accompanied individual bishops or groups of bishops from various countries. Others were formally appointed as advisers to the whole Council.

Father Joseph Ratzinger, now Pope Benedict XVI

Pope Benedict XVI

Benedict XVI is the 265th and current Pope, by virtue of his office of Bishop of Rome, the Sovereign of the Vatican City State and the leader of the Catholic Church as well as the other 22 sui iuris Eastern Catholic Churches in full communion with the Holy See...

, served as peritus to Cardinal Josef Frings, Archbishop of Cologne, Germany, while Hans Küng

Hans Küng

Hans Küng is a Swiss Catholic priest, theologian, and prolific author. Since 1995 he has been President of the Foundation for a Global Ethic . Küng is "a Catholic priest in good standing", but the Vatican has rescinded his authority to teach Catholic theology...

 was a peritus for the Council, rather than for an individual Bishop. The influential German theologian Father Karl Rahner

Karl Rahner

Karl Rahner, SJ was a German Jesuit and theologian who, alongside Bernard Lonergan and Hans Urs von Balthasar, is considered one of the most influential Roman Catholic theologians of the 20th century...

 S.J. served as peritus to Cardinal Franz König

Franz König

Franz König was an Austrian Cardinal of the Roman Catholic Church. He served as Archbishop of Vienna from 1956 to 1985, and was elevated to the cardinalate in 1958...

 of Vienna. John Henry Newman refused an invitation to be a peritus at the First Vatican Council

First Vatican Council

The First Vatican Council was convoked by Pope Pius IX on 29 June 1868, after a period of planning and preparation that began on 6 December 1864. This twentieth ecumenical council of the Roman Catholic Church, held three centuries after the Council of Trent, opened on 8 December 1869 and adjourned...

.

The periti often advocated ideas of reform in the Church and were often at the center of debates with some of the more traditional scholars from the Coetus Internationalis Patrum

Coetus Internationalis Patrum

The Coetus Internationalis Patrum was a study group of the conservative-minded bishops at the Second Vatican Council...

.