I believe that until a fetus can survive outside the mother's womb it is a part of a woman's one body (and hers to do with as she pleases). These trimesters (as you know) are arbitrary distinctions with little basis in medicine. Your argument is sound, I just disagree with the legal distinction.

To answer the question: anything post survivability outside the womb should be considered a double homicide, anything prior is a single homicide. The trick is determining when post survivability is.

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In this country, we don't need reasons to make things legal; we need reasons to make things illegal. - Startup