Of course it is. Our Constitution makes the distinction between innocent human life and those who are guilty of a capital crime.
It's not a crime to kill a person who is completely innocent of any capital crime if he steps out in front of your car on the freeway.
Don't get me wrong, I'd love to see the unborn get some manner of due process as persons rather than as property, but simply declaring the unborn as "persons" isn't going to be a pro-life panacea.
If that is achieved, I expect the pro-aborts will just pass laws saying that killing an unborn person is "justifiable homicide."