Ok.....In this case, the exercise I will leave to the reader is to go back and see if the series of responses makes sense, and exactly where the subject got changed. There was a different subject being discussed a little bit ago which I will ignore unless someone returns it to that point.
However, now that I know what you mean, I will try and address what you mean, regardless of how we got there. If I miss something important, I am sure you will correct me, and it's even fairly likely someone will beat you to it.
Personhood of embryo, fetus, fertilized egg, or organism with human DNA at any point prior to birth.....
At what point does that organism become a "person", or a "human being". As far as I know, those two terms are synonymous.
I don't know the answer to that. I don't know if anyone knows the answer to that. I don't even know if anyone even truly understands the question. I would answer, "When it becomes sentient", but I can't tell you when that is or how to test for it, and that's only my opinion anyway. So what does that imply about whether it has the right to life?
It doesn't imply anything, because the question about becoming a person hasn't been answered.
However, there is a related question that is more important. That question involves legality. At what point can that organism be treated as if it were a person with legal rights, particularly the right to life? That is not the same question as when it becomes a person, and the distinction matters.
As with all legal questions, the answer should found in the law. We look in the Constitution first, because any answer found in that document supersedes any other US law. However, there's nothing in there where the question can be answered.
We can look to tradition. However, in order to go back to old tradition, we would have to go back to a time when they didn't even know that there was such a thing as a fetus. Roe v. Wade went back there, but ended up citing a guy who presided over sentencing witches to death. Surely we can't take that seriously, can we?
Or, we can look to statutory law.
It is my opinion that in cases where there is no clear guidance in the Constitution itself, deference should be given to the legislature.
I'm willing to extend, interpret, and go beyond the original intention of those who wrote the Constitution and its amendments in a lot of cases. As I have said, I think there are a lot of things implied by the text even if they are not specifically in the text. One poster here noted that some of those things implied by the text have been developed over the decades, and even centuries, into the doctrines that have been articulated by the court. I agree with that.
However, I cannot see where the question of the beginning of the right to life of a fetus is answered in the Constitution. I don't think the answer is implied anywhere. Therefore, I think it should be the subject of a legislative answer, rather than a court ruling.
As for whether those things in the petri dish at the fertility clinid are "human beings" or not, I don't think so. But why should my opinion matter more than the next person's? Err.....uh.....next person capable of casting an informed ballot in an election.