Human development always tends to be a political tap dance. We need to establish a time that a human being is actually a human being. Is it at conception? Is it at a different time? If we could agree on a time then the abortion issue could be once and forever resolved. Abortions would be considered legal from such and such a time and after that time considered to be illegal as a protection to the unborn baby. However, due to the political hot potato this issue has created it will never happen. Abortion will always be a spear that is thrown by those that agree to the procedure and by those that find the procedure appalling. Doesn't seem to be any room for compromise.
They can establish whatever timeline they want.... it will not stop Catholics (and many other churches) from taking the stance that life begins at conception. To many of us, it's not about a legal definition, it's a moral one. And, in my belief system, life begins at conception... what happens to that life, once created, is for God, not man, to decide.