 Liénart, who participated in the 1939 papal conclave, was elected President of the French Episcopal Conference in 1948, representing the Catholic Church in France, and remained in that post until 1964.An elector in the 1958 papal conclave, he was named the first Territorial Prelate of "Mission de France" on 13 November 1954 and later resigned from this post in 1964.An active participant of the Second Vatican Council (1962–1965), Liénart was a leading liberal voice at the Council and sat on its Board of Presidency.