John Courtney Murray was called to the council in April 1963 at the request of Cardinal Francis Spellman of New York (who was otherwise a theological conservative) to be a "peritus", despite Ottaviani's well-known animosity towards him. Much of the material used by various bishops, especially American bishops, on the subject was drafted by Murray. Conflict over a possible declaration on religious liberty continued during this session, with the current draft taken off the agenda at one point during the fall, then placed back on it in response to pressure from the American bishops.