Upvote:5
Back in 1967, the 1917 Code of Canon Law still in effect. Divorce alone was never a cause for excommunication. This remains in force even in the 1982 Code of Canon Law. The 1917 Code did allow for the excommunication of those who divorced and remarried without an annulment. However, this excommunication was not automatic, except in the United States of America. The bishop had to formally excommunicate the individual.
If your mother lived in the United States, there was a local automatic excommunication for those who were divorced and remarried, but this was not the universal Church Law. You do not state where your mother was residing when this automatic excommunication occurred and it is important to us in order to answer your question accurately. (One could presume it was in the USA, as your father was a draft dodger for the Vietnam War.) For example, in 1884, the United States Catholic bishops established a regional law that automatically excommunicated those who divorced and remarried without an annulment. Again you do not mention if your mother claimed she was excommunicated for simply divorcing your father or if she had remarried, thus incurring this penalty according to the Law as it existed in the US at the time!
Divorce alone was never a cause for excommunication. Divorce and remarriage without an annulment did have the potential for penalties.
In 1884, the United States Catholic bishops established a regional law that automatically excommunicated those who divorced and remarried without an annulment. It did not affect those who were only divorced, and it definitely did not excommunicate any children from the marriage. This law applied only to Catholics in the United States.
The universal 1917 Code of Canon Law, which would have been in place in the early 1960s, did not contain a penalty of excommunication for those who were divorced. Nor were the children of the divorce excommunicated.
The 1917 Code did allow for the excommunication of those who divorced and remarried without an annulment (canon 2356). However, this excommunication was not automatic. The bishop had to formally excommunicate the individual. The bishop first had to warn the person to separate from their civil marriage spouse, and if the person refused, the bishop was then to excommunicate the person. But this would not have applied to the children.
Even if your mother had been divorced and civilly remarried and either automatically or formally excommunicated, it would have been a moot point by 1977. In 1977, Pope Paul VI rescinded and halted all excommunications for the divorced and civilly remarried.
On November 10, 1977, Pope Paul VI agreed to halt, retroactively, the automatic excommunication of divorced and remarried Catholics in the US. See: Vatican Eases Excommunication Rule