St. Jerome Visited by Angels, by Bartolomeo Cavarozzi (1587-1625) [public domain / Wikimedia Commons]
Jerome is the first of the Western Fathers to deny the inspired status of the Deuterocanon; the first to unabashedly designate them apocrypha instead . . . Jerome’s new canon was an innovation — and he knew it. (p. 142)
Protestant apologists often attempt to make Jerome the spokesman for a large silent majority of knowledgeable Christians in his day; this opinion is supported by no evidence whatsoever. Protestant scholars have long admitted that Jerome was essentially alone in his opposition to the Deuterocanon . . . It was also a decisive break from the practice of the ancient Christian Church. (p. 145)
But even with Jerome, there were several anomalies (or changes of mind or vacillations?), of such a nature that they would shock many a Protestant who rely on him as a “champion” in opposing the Deuterocanon. Michuta enumerates several of these curious inconsistencies:
He . . . flatly denies that Tobit is part of the canon,  although elsewhere he cites it without qualification!  . . . Jerome adopts the popular convention in his Letter to Oceanus by quoting Baruch as a voice made by “the trumpets of the prophets.”  Sirach is both rejected and quoted as Scripture,  although it is formally quoted  and occasionally used without qualification.  Wisdom is also occasionally formally quoted.  Jerome even attributes the passages from Wisdom to the Holy Spirit.  Maccabees is used without distinction.  Jerome at times alludes to the Deuterocanonical sections of Daniel in his letters.  Deuterocanonical passages from Esther are likewise quoted.  . . . he lists Judith as one of the virtuous women of sacred Scripture . . . . Prologue to John.
 Commentary in Eccles. 8.
 Letter 77:4.
 Commentary on Isaiah, Book 2, 3:12; Letters 77:6: 108:22; 118:1; 148:2,16,18.
 Commentary on Jeremiah, Book 4, 21:14; Commentary on Ezekiel, Book 6, 18:6; and Letter 64:5.
 Commentary on Isaiah, Book 8, 24:4; Commentary on Ezekiel, Book 6, 18:6; Letter 57.1 To Pammachius; and Letter 125.19, To Rusticus.
 Commentary on Isaiah, Book 1, 1:24; Commentary on Zechariah, Book 3, 14:9; and Commentary on Malachi, 3:7 ff.
 Commentary on Galatians, Book 1, 3:2 . . . and Breviarium in Psalmos, Ps 9.
 Against Pelagians, Book 2:30; Letter 7, To Chromatius, Jovinus and Eusebius.
 Letter 3, 1 To Rufinus the Monk; Letter 22,9-10, To Eustochium; Letter 1, 9 to Innocent.
 Letter 48, To Pammachius, 14. Letter 65,1.
(Ibid., 149-150; my own footnote numbering)
Gary Michuta [see also his Facebook page] now has a second book on this subject, called, The Case for the Deuterocanon: Evidence and Arguments (2015). His two volumes are the very best current Catholic sources available regarding the deuterocanonical books.