1) Pope Benedict XVI wrote about their role, as noted on p. 44 of the Lampstand book on capital punishment, Capital Punishment & Catholic Social Teaching: A Tradition of Support:
“…the Holy Father has remarked on the teaching authority status of the episcopal conference:
“The decisive new emphasis on the role of the bishops is in reality restrained or actually risks being smothered by the insertion of bishops into episcopal conferences that are ever more organized, often with burdensome bureaucratic structures. We must not forget that the episcopal conferences have no theological basis, they do not belong to the structure of the Church, as willed by Christ, that cannot be eliminated; they have only a practical, concrete function. No episcopal conference, as such, has a teaching mission; its documents have no weight of their own save that of the consent given by the individual bishops.
“It is a matter of safeguarding the very nature of the Catholic Church, which is based on an episcopal structure and not on a kind of federation of national churches. The national level is not an ecclesial dimension.” (Ratzinger, J. Cardinal with Vittorio Messori. (1985). The Ratzinger report: An exclusive interview on the state of the Church. San Francisco: Ignatius Press. pp. 59-60)
2) He again spoke about their proper role, as reported by Catholic News Service.
“Vatican City, Nov 15, 2010 (CNA/EWTN News) -- A national conference of Catholic bishops exists so that pastors of the Church might "share the fatigue of their labors." But, according to Pope Benedict XVI, those national conferences can never substitute for an individual bishop's authority and duty to guide his people.
“The pope turned a Nov. 15 address to a group of bishops from Brazil into a lesson on the function of the bishops' conference.
“The Catholic bishops of the world are divided into bishops' conferences depending on their geographic locations and language groups. For example, the more than 400 bishops of the United States, form the U.S. Conference of Catholic Bishops; the English and Welsh bishops are combined into a single bishops' conference.
“Since the Second Vatican Council (1963-1965), some critics have argued that bishops' conferences have assumed too much influence in the lives of local churches and in some cases have diminished the authority of local bishops.
“In his address, Pope Benedict reminded the Brazilian Church leaders that “the counselors and structures of the episcopal conference exist to serve the bishops, not to replace them.”