That must be why we see responses like this (link to response) from Roman Catholic human being Mark Shea. Of course! How could we be so dim! Christifideles Laici overrules 800 years of tradition, and the moral basis underlying the canonical provisions we previously identified (link).
But wait, does Christifideles Laici actually contradict those earlier documents in any way?
Does it permit any lay person to "engage in dispute, either private or public, concerning the Catholic Faith" contrary to Pope Alexander IV's decree? Does it permit any lay person "publicly make a speech or teach, thus investing himself with the dignity of a teacher" contrary to the degree of the Quinisext Ecumenical Council? Perhaps you have to read between the lines with special golden spectacles.
So let's see, when a really old document matches what Mr. Shea believes, it's those evil Calvinists trying to throw off tradition, but when the 800 year old document disagrees with Mr. Shea, it's so much out-dated rubbish.
P.S. For those who haven't yet become accustomed to my style, I think it is absolutely absurd to think that it was immoral of laity to teach 800 years ago, but perfectly fine, in fact their duty, to do so today. Morality doesn't change, because God (the God of the Bible) doesn't change.