The Holy See has always taught that anonymous letters are to be disregarded
and have never recognized that they have any probative value.
On May 7, 1923, the Sacred Congregation for the Sacraments issued the decree,
Doctrina Catholica. Its rule 77, #1 states, “No document is entitled to credit
unless it is proved to be authentic and genuine.” (cfr. Acta Apostolicae Sedis,
Vol. 15, pp. 389, ff.)
The Sacred Congregation for the Sacraments, August 15, 1936, promulgated the
decree, Provida Mater. Article 165 states, “Anonymous letters and other
anonymous documents of any kind usually cannot be considered as an indication,
unless, and to the extent that, they report facts which can be proved from other
sources” (cfr. AAS Vol. 28, pp. 313, ff.).
The jurisprudence of the Roman Rota is fully concordant with these statements
(cfr. Sacra Romana Rota: Decisiones 22, n. 9, pp. 373; Vol. XXV, decision 35, n.
12, p. 303).
The Supreme Tribunal of the Apostolic Signatura has the same philosophy of
jurisprudence with regard to documentation (cfr. Private Reply, Apostolic
Signatura, November 24, 1973; reported in Communicationes pro Religiosis, Vol.
56 (1975) pp. 373-383; and Periodica, Vol. 64 (1975) p. 296-303.
Many commentators express the same opinion. Wanenmacher writes, “As long as
the authorship of the document has not been duly established, there is no legal
proof forthcoming.” Anonymous letters cannot be brought as evidence in the
trial. (cfr. Francis Wanenmacher, Canonical Evidence in Marriage Cases,
Philadelphia, Dolphin Press, 1935, p. 236).
The same opinion is also articulated by Felix Cappello, SJ (cfr. Summa
Iuris Canonici, Vol. III. Edition 4, n. 280) and Conte A. Coronata (cfr.
Institutiones Iuris Canonici, Vol. III, Edition 5, n. 1330).