The main argument for overturning Roe v. Wade and its successors is that no right to abortion can plausibly be derived from the text, original understanding, history, or structure of the Constitution. Robert VerBruggen is right that the unworkability of the Supreme Court’s abortion jurisprudence — its shifting details and rationales, its lack of predictability and guidance for legislators — is a subordinate argument against it. If that jurisprudence were grounded in the Constitution, it wouldn’t be much of an argument against it at all.
We get to the workability argument only after establishing that Roe, Casey, et al are not so grounded. It is not especially hard to establish that conclusion, and I suspect that we already have a majority of the Supreme Court who agree with it. The constitutional holding and, even more, reasoning of Roe have been notoriously hard to defend. That’s why so much of the defense of the Court’s abortion jurisprudence rests on its status as precedent. The workability argument attempts to undermine that status. By persuading wavering justices, it could — as I said in an article about this issue that VerBruggen mentions — prove decisive.
VerBruggen also notes that workability can be an issue even when the Constitution marks out a right. The Court has thus far failed to clarify what restrictions on guns are compatible with its reading of the Second and Fourteenth Amendments. When marking out a judicially enforceable line between what governments can and cannot do is sufficiently difficult, that is a reason for the justices to treat a constitutional provision as non-justiciable.
But it seems to me that the problem is significantly worse when, as in the case of abortion, the right isn’t in the Constitution to begin with. If we had a constitutional provision reading, “The right to abortion is fundamental and shall not be infringed,” it would seem to be a fair inference that it can’t be restricted even late in pregnancy. But the justices have had too many qualms — whether moral or political — to take the line that the Constitution contains that line in invisible ink, and stick to it. And since the justices are just making it up as they go, they can entertain the idea that viability marks a constitutionally important date, that the right deserves less (or sometimes more) protection than other rights that are mentioned in the Constitution, and so on.
The unworkability argument is thus related to the underlying constitutional argument, while it also buttresses it.