But the political debate over abortion is not a debate over morality. It is a debate over legality.
Today's pro-life movement goes beyond arguing that abortion is immoral to argue that abortion should be punishable. Morality and punishability are two very different categories. ...
It is the demand that abortion be punished that divides America so passionately.

So Frum is wrong: It is not really the legal question of abortion that "divides America so passionately," but the ethical question. For if an ethical consensus was truly reached, a legal consensus would follow naturally.
Frum thinks the pro-life movement should stop trying to prohibit abortion, and instead focus on reducing the number of abortions without the force of law. Of course, we will continue working to reduce abortions using education, persuasion and compassionate assistance. But Frum does not seem to understand that the pro-life position, properly understood, is necessarily political, just as the movements to end slavery, bring about women's suffrage, and ensure civil rights for black Americans were necessarily political. Basic justice requires that human beings not be treated as property; that women, who are equal in fundamental human dignity to men, be equal participants in democracy; and that people not be discriminated against on the basis of skin color. It is not enough to try to use persuasion to reduce the incidence of some people enslaving other people under a legal regime that permits slavery; even if slavery did not in practice exist, such a legal regime would be gravely unjust, for it says that human beings may be treated as property for the benefit of others.
So it is with abortion. The truth of the pro-life position entails that we work to restore legal protection for innocent human beings at all developmental stages, including the unborn. It is a matter of justice.