Abortion opponents, like their adversaries, recognize the potential for electoral backlash if the court reverses Roe outright. Many would prefer abortion rights to die gradually and quietly. Merely by interpreting Casey to allow increasingly restrictive laws, the Supreme Court can stealthily smother choice without appearing to deliver a death blow.

Senator Susan Collins, Republican of Maine, said this summer that she could not support a nominee who had “demonstrated hostility to Roe” or to “established precedent.” Judge Kavanaugh reportedly told Ms. Collins recently that he considered Roe to be “settled law.” These statements should reassure no one. Casey, not Roe, is the established precedent that matters here. And it seems more likely that abortion rights will die a death by a thousand cuts through restrictive state laws allowed under Casey than by a reversal of Roe. Either way, a vote for Judge Kavanaugh is a vote to diminish reproductive freedom.

It is also a vote to advance a larger agenda. Over several decades, the conservative legal movement has linked opposition to reproductive choice with constitutional theories that enhance the rights of corporations at the expense of human beings. Conservatives have tethered the anti-abortion cause to a selective libertarianism that opposes government regulation of business but authorizes expansive executive power and state intrusion on individual liberties. Judge Kavanaugh would not have passed Federalist Society muster if he did not demonstrate allegiance to these principles.

With this confirmation vote, then, much more than abortion rights hangs in the balance. So does the country’s ability to fight voter suppression, political corruption and racial intimidation; to protect clean air and water; to ensure safety for workers and consumers; to combat climate change; to enact sensible gun laws; to voluntarily integrate public schools; to provide necessary health care and preserve a basic social safety net; to protect civil rights and liberties; and to safeguard the integrity of all families.

Americans who put aside their qualms and voted for the president to secure Supreme Court justices who would end legal abortion may pay a high price for their choice. With one more justice, Mr. Trump’s Republican Party will fully control all three branches of government, eliminating the last check on his power.

It matters little, therefore, what Judge Kavanaugh says to senators about Roe or “settled law.” Conservatives have learned the lessons of Casey too well to permit the appointment of another justice in the Anthony Kennedy mold. And abortion rights are one of many inevitable casualties of this appointment. Senators who vote yes will bear responsibility for all of them.

Serena Mayeri is a professor of law and history at the University of Pennsylvania Law School.

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