Forty-five years after Roe v. Wade was decided, the right to abortion that the Supreme Court discerned remains controversial and disputed.

The expectation of legal abortion is deeply embedded in U.S. law and practice. Many states were lifting restrictions on the procedure even before Roe. Justice Harry Blackmun's landmark decision seized upon an existing social trend. According to a May 2017 Gallup poll, 78 percent of Americans think abortion should be legal in some or all circumstances. A constitutional amendment against abortion — favored by many social conservatives — is a practical impossibility.

But the Supreme Court created a legal regime more extreme than the consensus. The dogged antiabortion activists who return to Washington each year to protest Roe during the March for Life are not alone. In the same Gallup poll, 49 percent of Americans agreed that abortion is "morally wrong" (compared with 43 percent who find it "morally acceptable"). Just 29 percent believe abortion should be legal in every circumstance. A number of states have moved to restrict abortion at the edges — requiring abortion clinics to meet the standards for ambulatory surgical centers, mandating that abortion providers obtain visiting privileges at local hospitals, restricting the procedure after the fetus can feel pain.

Why does this issue refuse to fade from our politics? One reason concerns Roe itself, which was (as Justice Byron White put it in his dissent) "an exercise in raw judicial power." Blackmun's ruling does not hold up well on rereading. His system of trimesters and viability was (and is) arbitrary and medically rootless, a fig leaf covering an almost limitless abortion right. Blackmun's weak argument largely substituted for the democratic process in 50 states. Fiat replaced deliberation and democratic legitimacy. This was a recipe for resentment and reaction.

But judicial fiat can't be a sufficient explanation. The Obergefell decision legalizing same-sex marriage in every state was also sweeping. It has produced almost no political reaction. The contrast to Roe could hardly be starker. And the explanation is rather simple: All the great civil rights movements have been movements of inclusion. The first modern civil rights campaign — militating for the end of the British slave trade — set the pattern with its slogan: "Am I not a man and a brother?" Susan B. Anthony asked: "Are women persons?" In the most rapidly successful civil rights movement of our time, gays and lesbians came out to show their communities that LGBT people were their friends and family members. All these efforts expanded the circle of social welcome and protection.

The abortion rights movement, in contrast, is a movement of autonomy. Its primary appeal is to individual choice, not social inclusion. And the choice it elevates seems (to some people) in tension with the principle of inclusion. A fetus is genetically distinct from the mother, is biologically human and has the inherent capacity to develop into a child. This makes it different from a hangnail or a tumor. At what point does this developing human life deserve our sympathy and protection? When neurological activity develops? When the fetus can feel pain? When a child is born? When an infant can think and reason? All these "achievements" are, in fact, scientifically and ethically arbitrary. They don't mark the start of a new life, just the development of an existing life.

It is the antiabortion movement that appeals to inclusion. It argues for a more expansive definition of the human community. It opposes ending or exploiting one human life for the benefit of another. There are heart-rending stories that prevent the simplistic application of this approach. But most of the antiabortion men and women I know have the genuine and selfless motivation of trying to save innocent lives.

An appeal to choice is undeniably powerful in our time. It seems to be the age of autonomy on both left and right, from abortion rights to right-to-die laws to marijuana legalization. The assertion of a right is often enough to end an argument. But there is an ethical and political alternative, emphasizing an inclusive concern for the common good and solidarity with the most vulnerable members of the human family. Martin Luther King Jr. called this "the beloved community." It emerges not through the assertion of autonomy, but through the acceptance of our shared humanity and of the loyalty we owe one another.

Both of these priorities — autonomy and inclusion — are strongly present in U.S. history. The abortion debate falls along this enduring divide, producing a social conflict that will only be managed, not settled.

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