Any canon (list) of the works of any author is a reflection of historical fact.
If I come along and say that Macbeth was not written by Shakespeare, I am disputing the accepted canon of Shakespeare, and saying that it should be revised so as not to include that particular play.
If someone comes along and says that James is not written by inspiration of the Holy Spirit, they are disputing the accepted canon of Scripture, and saying that it should be revised so as not to include that particular epistle.
No one has the "authority" to put books in, or take books out of the canon: we simply have a duty to recognize the truth of Divine inspiration that is exhibited in the 66 books, in two testaments that we call "The Bible."
So, the Roman Catholics do not have the authority to add books to the Old Testament, and the modernists do not have the authority to remove books from the New Testament.
The Shepherd of Hermas should not be included in Bibles, because it is not divinely inspired. It's not as though it hasn't been voted into Biblehood yet - it simply wasn't inspired.