In 1229, the laity were officially forbidden by the Council of Valencia to have or read what it now calls "God's Word".
"A first version (the Pauline Index) was promulgated by Pope Paul IV in 1559, and a revised and somewhat relaxed form (the Tridentine Index) was authorized at the Council of Trent. The promulgation of the Index marked the "turning-point in the freedom of enquiry" in the Catholic world."
Adolf Hitler's Mien Kampf, on the other hand, never made it into that catalogue. And it appears that it never will, because, after "the final (20th) edition appeared in 1948", the Index "was formally abolished on 14 June 1966 by Pope Paul VI". Officials of the church, however, made the point at the time that the Index retains its moral force "inasmuch as it teaches the conscience of Christians to beware, as required by the natural law itself, of writings that can endanger faith and morals, but it (the Index of Forbidden Books) no longer has the force of ecclesiastical law with the associated censures."