There is a small debate on the Moral Theology forum and this situation is was presented. You have a married, post-menopausal couple and the husband has MSRA. Normal marital relations would result in infection of the wife. Would it be licit for the couple to have marital relations with a condom to prevent the spread of the infection since it is no long possible for them to procreate and would such relations still be unitive?
You have two separate questions here: The one in the post title (“Can contraceptive devices EVER be used licitly?”) and the specific hypothetical you have posed.
In answer to the hypothetical, this is a situation moral theologians in the Church have been exploring but the Church has made no definitive announcement that use of condoms in such a situation would be licit. In the absence of further clarification from the Church, the couple should fall back on the ordinary teaching of the Church in this matter and the ordinary teaching is that contraceptives may never be used during marital relations for the purpose of frustrating the marital act. Even if the couple is not able to procreate children, condoms do block the unitive aspect of marital relations.
Interestingly enough, though, the answer to the question, “Can contraceptive devices EVER be used licitly?” is “Yes.” If the contraceptive device is not being used as contraception, it may well be perfectly fine to use it. One example of this would be the perforated condom prescribed to couples undergoing licit fertility treatments so that a sperm count may be done. The condom captures some sperm for testing purposes while allowing other sperm to pass through, which means that neither the procreative or unitive aspects of the marital act are frustrated.