Is there a constitutional principle so sacrosanct that it can abide no exceptions? Perhaps the First Amendment? Nope. Courts have placed reasonable restrictions on free speech and the practice of religion. You can’t libel someone, nor can you sacrifice live animals. The Second Amendment? No again, as any number of gun laws attest. One can find reasonable exceptions to just about every constitutional principle.

But 43 years ago, trawling through the penumbra and emanations of the Constitution, Justice Harry Blackmun found an inviolable right that had somehow evaded the Founding Fathers: the right to kill a child in utero—mere inches from being fully born, even—for any reason or no reason.