The post (at Balkinization) is here; as I've mentioned before, I haven't studied the issues in this case closely enough to speak to this myself, but Prof. Lederman is a leading constitutional expert, and his thoughts struck me as much worth passing along:
1. Colorado Is Not "Enforcing" or "Implementing" Section 3.
The briefs of all four of the parties in the Supreme Court (and those of many amici, as well) proceed on the assumption, articulated repeatedly in their briefs, that if Colorado were to omit Donald Trump's name from its presidential primary ballot—something that, as I explain in this post, Colorado has not in fact done and is unlikely to do—the state would acting to "enforce" or "implement" Section 3 of the Fourteenth Amendment. Indeed, some of the parties' arguments take this as a jumping-off point, and depend upon it.
But it's wrong. Colorado isn't purporting to "enforce" Section 3, and states don't have any power to enforce its disqualification directive with respect to federal officers.
To be sure, a state has the power to enforce Section 3 with respect to state officers who are subject to Section 3's disqualification rule. Relevant state officials or courts with statutory or state constitutional authority, for example, can refuse to appoint a Section-3-disqualified person, or remove such a person from office. And, if state law prescribes it, a state legislature might be able to remove state legislators, as well as other state officers by way of impeachment, etc.
But a state does not have any legal authority—nor, to my knowledge, has any state ever claimed such power—to enjoin a disqualified federal official from holding office, or to remove him or her from such office….
Once one understands that Colorado is simply enforcing its own state-law rule prescribing exclusion of ineligible candidates from primary election ballots for purposes of state election management—a rule not confined to presidential candidates—one can see that Trump's argument that Colorado is imposing an additional "qualification" for Trump to hold office (according to Trump, Colorado has effectively required a candidate not to be subject to Section 3 ineligibility at the time of the primary election rather than on January 20, 2025) rests upon a category error: By declaring that candidates for President may not appear on its presidential primary ballot unless they meet certain conditions (including apparent eligibility to hold the office), Colorado is no more imposing extraconstitutional "qualifications" on persons holding that national office than Virginia did in 2012 when it excluded Rick Perry from its presidential primary ballot because he failed to timely submit the necessary number of voter signatures. See Perry v. Judd, 471 F. App'x 219 (4th Cir. 2012). (I pulled that example from Derek Muller's excellent amicus brief.)
2. Colorado Also is Not (Yet) Exercising Its Authority Under Article I's "Electors" Clause
