The pending retirement of Justice Anthony Kennedy from the Supreme Court has provoked alarm among defenders of women's reproductive rights. They worry that his successor may well be willing, as Kennedy himself was not, to overturn Roe v. Wade, the landmark 1973 decision establishing a constitutional right to abortion. This concern is fully justified. If Roe were overturned, abortion would immediately revert to being an issue decided at the state level, and as many as 20 states may be poised to ban the procedure outright.

But this isn't even the worst-case scenario for abortion rights on a post-Kennedy Supreme Court.

What if a conservative majority of the Court rules not that abortion should be decided by state legislatures, but that the procedure should be banned outright at the federal level as an assault on the personhood (and hence constitutionally protected, inviolable rights) of the fetus?

Far-fetched? Perhaps. But we simply don't know how sympathetic the Court's current crop of conservatives might be to such arguments, just as we're unlikely to receive much illumination about the question during confirmation hearings for President Trump's nominee to succeed Kennedy. (Nominees have long eschewed answering detailed, specific questions about their views on the most controversial issues likely to come before the court, for fear of sinking their prospects of receiving an affirmative confirmation vote.)

The reality is that such arguments about the personhood of fetuses are in wide circulation among conservatives and anti-abortion activists — and that they have gained considerable traction over the past two decades, eclipsing the originalist arguments on which Robert Bork would have drawn in seeking to overturn Roe had he been confirmed back in 1987, and which Antonin Scalia regularly made in justifying his own contempt for the 1973 decision.

That's why everyone who cares about the reproductive freedom of American women needs to be aware of the present danger — as should Republicans, who may end up inadvertently reaping the political whirlwind with their votes to confirm a justice who could conceivably declare unconstitutional a procedure that fewer than one-fifth of Americans want to see banned outright.

An older, now dying, generation of conservative jurists based their opposition to Roe on a positivist argument: The Constitution says nothing about abortion (or a right to marital privacy, which was established in the Griswold decision of 1965, and on which the right to an abortion was based in Roe). Therefore there is no possible constitutional right to abortion. Which means that, like any non-constitutional issue, abortion should be left in the political arena, with states deciding whether or not to allow it, and whether and how to regulate it.

But for an influential faction of pro-life intellectuals, that position is morally unacceptable — and for good reason. If an abortion really is an extrajudicial act of lethal violence against an innocent human being, then allowing democratically elected legislatures to decide whether or not to treat this act as a crime seems to be monstrous. Murder is murder, whether or not the voters of a state recognize it as such. To allow the legislatures of more liberal states in a post-Roe order to keep abortion legal would therefore be, in the words of influential abortion opponent Robert P. George, a betrayal of the "substantive principle of equal worth and dignity that is the moral linchpin of democracy." For that reason, the fully pro-life position requires the unborn to be defined as persons covered by the equal protection clause of the 14th Amendment.

When George proposed this view, in a controversial symposium published 22 years ago in the conservative religious magazine First Things, it was an outlier position among conservatives. Bork himself strongly rejected it in the pages of the same journal as recently as 2004. Yet in intervening years the view has gained in power and influence among conservatives and even made its way, at the level of premises, into federal law.

The Born Alive Infant Protection Act of 2002 and the Unborn Victims of Violence Act of 2004 both define fetuses as persons — the latter by declaring that anyone who causes death or injury to a child in the womb while causing death or injury to the child's mother will be charged with a second offense. From the point of view of this rights-bearing person in utero, what, exactly, is the difference between an assailant and a doctor performing an abortion, both of whom violate its right to life?

Republicans have made many subsequent attempts to plant the premise of fetal personhood in both state and federal law, including in the tax bill President Trump signed into law last December. The reason is obvious: Each time an unborn child is presumed in American law to be a rights-bearing person is potential ammunition to justify a future Supreme Court ruling that declares fetuses to be persons subject to equal protection of the law.

Would five conservative justices post-Kennedy vote to protect the unborn under the 14th Amendment? There's no way to know for sure. But even if we assume that only three of them (say Justices Clarence Thomas, Neil Gorsuch, and Amy Barrett) were willing to do so in a concurrence to a decision overturning Roe, that would plant perhaps the biggest premise of all — establishing in the text of a Supreme Court opinion that fetuses are persons with rights. That in itself could serve as the foundation for a future, far more sweeping decision once conservative opinion evolves still further in this direction.

Pro-lifers would rejoice at such an eventuality, but Republicans better hope it never comes to pass. The GOP is already a minority party on a growing list of issues, with officeholders increasingly reliant on the manipulation of our system's abundance of counter-majoritarian norms and institutions to gain and hold political power. But few issues place Republicans in such a tiny minority box as support for banning abortion outright — a position affirmed by just 18 percent of the country.

If Republicans aren't careful, they could end up fulfilling the most fervent wishes of an especially powerful faction of their base while severely and irreparably antagonizing just about everyone else in the country.