Just had a quick thought on authority that I wanted to write out. When Christians call Scripture the Word, they point to its identity with and revealing of Christ the Lord. By doing so, we attribute to Scripture an abiding transcendence. That is, no interpretation of Scripture, regardless of the detail given, could ever fully replace Scripture. This makes sense when we consider revelation to be the place of our relationship with God and not a mere list of propositions that are true. This being the case, I would argue then that no interpretation of Scripture could bear the authority of Scripture. Any interpretation of Scripture, even those we consider vital and necessary to the life of the church, remain tenuous to some degree because they lay within the range of Scriptural critique. The Word transcends all statements made about itself. If this is true, then so called authoritative interpretations of Scripture are limited in scope to their pragmatic function with the church and would be fallible. This sense of authority exists insofar as the statement (or act) guides the community into the life of Christ. (As a corollary, I would suggest that the omission of authoritative interpretations is deeply problematic since they constitute the prophetic witness of Christ.)
Not sure about the argument, but I do think that the text remains ever beyond the interpretation. Perhaps this is a hermeneutical authority separate from the ecclesial nature of interpretative authority.