This came to mind today while I was driving home from class. Don't ask me why; it just did.
Suppose there's a person (man or woman) who is a fervent right-to-lifer, someone who thinks that abortion is immoral and should be illegal, that it's wrong to deny a living person the opportunity to live, and that abortionists and the women having abortions are murderers. This person is on the way to a planned parenthood clinic to protest its continued existence. While she's driving on the street where the clinic is located, he or she momentarily looks away from the road, and in that instance, rear-ends a woman who is there for an abortion appointment. As a result of the rear-end collision, the pregnant woman suffers a miscarriage.
The issue to consider is, in this right-to-lifer's mind, is he or she a murderer or manslaughterer? If this person stands by the mantra that "life begins at conception," then, the unintended death of the fetus via miscarriage as a result of the rear-end collision would (I think) have to be declared involuntary manslaughter. If the fetus is not actually "alive" in the legal sense (as it's currently defined), then, the miscarriage is an unfortunate accident, and one that had the same effect that the abortion she tried to stop would have had.