The fact that some abortions (might) cause no pain doesn't make them right, any more than a painless murder in other circumstances.

I do agree that the complete lack of a father's rights to object to the abortion of his offspring is a terrible thing.  Giving a father the right to insist on his child being born alive would be a good step in the right direction.  It would not go far enough.

Keeping abortion legal under any circumstances flies in the face of the previously mentioned "Freedom" and "Personal Responsibility" clauses.  Freedom, because abortion certainly does harm the aborted fetus, and absolutely denies it the freedom to live.  Personal Responsibility, because abortion is generally used as a way to avoid the consequences of being irresponsible with one's body; it's too inconvenient to be saddled with a baby, so we abort it.  This is completely at odds with any notion of personal responsibility.