The pro-life case for masturbation.
For some reason, I don’t see the Vatican buying this argument. IMO it is the pleasure derived from the act that the Vatican would be trying to prohibit and not the actual ejaculation (first time the word ejaculation has been used on this site) (that parenthetical was the second). If there was a method to remove the pleasure from the act, perhaps they would be more open to this reasoning. But what fun would that be?