A telling, but still unsatisfying, SCOTUS discussion of retroactivity during oral argument in Welch

As previewed in this post, yesterday the Supreme Court heard oral argument in Welch v. United States, which is principally concerned with the retroactive application of last Term's significant ruling in Johnson (authored by Justice Scalia) that the "residual clause" of the federal Armed Career Criminal Act was unconstitutionally vague.  I am deeply interested in this Welch case, not only because I helped with this law professor amicus brief in Welch, but also because I have authored this law review article to explain my view that traditional SCOTUS retroactivity doctrines — so called Teague doctrines — developed with unique concern for the importance of preserving the finality of convictions are not necessarily the best was to examine whether and when a new sentencing rule ought to apply retroactivity.

Helpfully, Rory Little has followed up his terrific Welch oral argument preview post at SCOTUSblog with this spot-on oral argument review post titled "Argument analysis: A likely decision in favor of retroactivity?."  Having read the full argument transcript in Welch (which is available here), I fell well positioned to assert that Rory's analysis is a much better and more enjoyable read, and it includes these essential insights at its start and end:

While it is not possible to describe the intricacies of retroactivity doctrine here — let alone wise if we want to keep our readers awake — it looks like last Term’s decision in Johnson v. United States will be declared to apply retroactively for all purposes, including on first and even successive (assuming they are timely filed) habeas corpus petitions. And as I explained in my preview, that result is likely, although not certain, to result in substantial sentencing reductions for a significant number of convicted federal defendants....

The law of retroactivity presents intellectual conundra that may never be fully settled.  The decision in this case is likely to be simply one more precedent in the wavering doctrinal line.  We will never know what Justice Harlan, or Justice Scalia, thinks of it.  But convicted federal felons whose sentences are reduced by five or more years will not care about the intricacies, while young law professors aspiring to tenure will have new grist for their mills.

Though I am no longer a young law professor, the intricacies of retroactivity doctrines as articulated in Teague and its progeny are a source of frustration and concern for me.  And the Welch oral argument leaves me concerned that the current Justices are going to be content to apply existing Teague doctrines in a quirky manner to a quirky case (as they have recently show they are wont to do in Montgomery v. Louisiana decided a few months ago).  As I suggest in this law review article, applying traditional Teague doctrines in retroactivity cases that involving only sentencing issues necessarily involves banging a square equitable peg into and round Teague doctrinal hole.  And yet, after reading the Welch transcript, it seems the Justices are for now content to just keep banging away.