"In the eighteenth century, Coke’s description “quick with child” (the point at which the child is first able to move, then considered to be the beginning of existence) was equated with “quickening” (the point at which the mother first feels fetal movement). This distinction was intended to protect prenatal life as soon as it could be discerned, not to exclude human life from protection prior to that point. Once again, “quickening was a flexible standard of proof—not a substantive judgment on the value of unborn human life.” The Roe Court made much of the quickening rule in its rush to dismiss the personhood of the preborn, but failed to see that the rule was merely a tool of criminal law, not a statement about the value of life prior to perceptible movement in the womb. The “quickening” distinction survived in common law until emergent medical science discovered “that human life began at fertilization,” allowing medical examiners to prove prenatal life and cause of death due to abortion with greater certainty. After this discovery in the early nineteenth century, British courts instructed jurors that “quick with child,” which had earlier meant “formed and animated,” now meant “from the moment of conception.” When determining whether to grant temporary reprieve from execution for a pregnant woman, for example, the court in Regina v. Wycherley81 reinterpreted common law to reflect that new scientific fact in 1838."