Unlike historic Protestants who believe the Church derives its authority from the Bible, RC teaches the opposite, that the Bible derives it’s authority from the Church, and that therefore the Church has the authority to interpret it.
Semantics aside, all doctrine is rooted in the Bible. Of course the Church interprets it, anyone who reads it interprets it, else it may as well be a random jumble of words, no? Part of being Catholic is working together so we arrive at the same, correct interpetation, all of us together. Not this in one church and that in the church down the road. Both can't be right. I think a lot of trouble comes from this sola scriptura notion. That runs you up against John 21:25 "Jesus did many other things as well. If every one of them were written down, I suppose that even the whole world would not have room for the books that would be written." So things external to the Bible, like tradition must be considered.
Now the Catholic view is that the Bible must be internally consistent, it can't mean one thing here and the opposite there. The Bible must be interpreted in a manner to be consistent. Further, since everything Jesus taught and did are not in the Bible, interpretation must also be consistent with other validated sources such as tradition.
That does not mean some other source can overrule the Bible. It's that if a passage can be read to mean this, that, or the other, which one conforms to the rest of the Bible and validated external sources.
As I understand it (and I haven't dwelt on it) this does not violate the original meaning of sola scriptura. Extrinsic evidence does not change the scripture but enhance our understanding of what scripture is really trying to say.
