First, the constitution does not define what is or is not a person. The declaration of independence establishes as a defining principle of this nation the idea that we are endowed by our creator, that is, we come into being with the right to life , liberty and the persuit of happiness. Those being in the order they are for a very specific reason.
Interesting how you cherry pick the words of Justice Blackmun in an attempt to make your point. If your point isn't made by the entire statement, in context, your point isn't made. Justice Blackmun said:
"The appellee and certain amici argue that the fetus is a "person" within the language and meaning of the Fourteenth Amendment. In support of this, they outline at length and in detail the well-known facts of fetal development. If this suggestion of personhood is established, the appellant's case, of course, collapses, [410 U.S. 113, 157] for the fetus' right to life would then be guaranteed specifically by the Amendment. The appellant conceded as much on reargument."
Later in the decision he says:
"Indeed, our decision in United States v. Vuitch, 402 U.S. 62 (1971), inferentially is to the same effect, for we there would not have indulged in statutory interpretation favorable to abortion in specified circumstances if the necessary consequence was the termination of life entitled to Fourteenth Amendment protection."
In 1972, an argument, of sorts, could be made that unborns were not, indeed, human beings. In fact, an argument could be made, at that time, that the unborn was a part of its mother's body. Medical science has come a long way since then and no credible medical source suggests that unborns are either part of their mothers body, or are not individual human beings at any stage of their development from zygote to mature individual reached sometime in the middle to late 20's.
At present, several men are in prison for killing pregnant women. They were charged and sentenced not only for killing the woman, but for killing the child as well. One can not be sentenced for manslaugher for killing a non person so legal precedent is established for the personhood of the unborn.
