How many federal prisoners might now be serving illegal sentences after Borden?

I will be blogging in a future post about just how current federal prisoners serving Armed Career Criminal Act sentences might seek relief from now-illegal long sentences based on the Supreme Court’s important ruling in Borden v. US, No. 19–5410 (S. Ct. June 10, 2021) (available here), limiting applicable ACCA precedents.  (Spoiler: they should not forget “compassionate release” as a means of seeking relief.)  But my inquiry for this post is the preliminary question in the title of this post: can we figure out how many federal prisoners might now be serving illegal sentences after Borden because they were sentenced on the basis of a reckless predicate ACCA offense?

Figuring out a precise answer to this question is very intricate, though it is aided greatly by this recent US Sentencing Commission report detailing in Figure 1 how many ACCA sentences have been handed down over the last decade.  Based on that data and with a bit of extrapolation, I think it possible that there could be as many as 10,000 persons (though likely somewhat fewer) in federal prison now serving ACCA sentences.  [UPDATE with better numbers: an astute commentor notes that the USSC report actually has a Figure 7 reporting that a “total of 3,572 offenders in
Federal Bureau of Prisons (BOP) custody as of June 27, 2020 were sentenced pursuant to the ACCA.”  A year later, I would guess that number is about the same.] However, I suspect the vast majority of those prisoners would not have clear or even viable Borden claims.  In fact, I would be tempted to guest that less than 1 out of every 10 ACCA prisoners has a strong Borden-based claim for undoing his sentence. 

But I am truly making a wild guess here, and I am eager to hear from folks in the field about whether they agree that only hundred of sentences may be potentially disrupted by Borden or if in fact it could end up being thousands.  Whatever the exact number, as I will explain in a future post, every ACCA defendant with a viable Borden claim should be thankful for the FIRST STEP Act making “compassionate release” motions available o bring directly to court.  But more on that will come in a future post.