The vote was the first time since Roe v. Wade that either house of congress has voted on a national late-term-abortion ban, yet days before the vote there was no certainty it would happen. Its last-minute metamorphosis from a much narrower bill is reflected in its formal title, “District of Columbia Pain-Capable Unborn Child Protection Act.” It had been opposed at various points by the House GOP leadership and elements of the pro-life movement, and it went on the calendar with just a few days’ notice. Many pro-lifers, inspired by the Gosnell case and other abortion-clinic scandals, were eager to prepare for the vote with extensive congressional hearings. Desirable as such hearings were and are in the larger battle for public opinion, the unexpected nature of the issue’s arrival on the House floor caught many Democrats flatfooted, with zero ability to minimize or obfuscate the starkness of their vote to permit the killing of viable babies.

The one thing certain about social issues is their unpredictability. In this latest surprise a social-conservative movement that has been on the defensive — with elite opinion universally declaring its irrelevance and some in the Republican establishment calling for the removal of these issues from the party’s self-definition — has suddenly been presented with a recorded vote that could put its foes in the position of defending a practice that most American voters find indefensible.