Consider the following hypothetical scenario. I recognise that it very likely to never occur, but I am interested more in the technical implications than in any actual possibility. Additionally, while the ethical questions involved are certainly interesting, I am specifically asking about the actual legal issues involved, not about the ethics of the situation (except so far as they might apply to the legal outcome).
A clause is added to the constitution declaring unambiguously that all unborn foetuses fitting a certain set of criteria are human beings with all the attendant basic rights etc.
A pregnant woman, whose unborn child matches the set of criteria exactly, but who absolutely, unequivocally and unambiguously believes that her unborn foetus is not a human being, procures an abortion.
Is the woman legally guilty of murder (or, if not, any form of homicide)?
I'm interested in any and all reasons for the answer being yes or no, but my main concern is the following:
The act of procuring an abortion, as I understand it, would satisfy the actus reus of murder, that is, the deliberate ending of a human life. However, if someone is genuinely convinced that they are not killing a human being (which includes the circumstance that what they are killing is not a human being), it would seem that they do not satisfy the requirement for mens rea for a murder conviction.
One might draw a parallel with a woman with postpartum psychosis who, while hallucinating that her six-month-old son is a monster, throws him from the balcony of an apartment building, killing him. In both cases, the woman involved causes the death of her child, but is totally convinced that she is not killing a human being.