This is a funny asterisk or footnote, but it's also a bigger issue. Did Trump, like the civil war secessionists, commit an insurrection against the US government? We could actually have an extended argument over whether his actions leading up to and on Jan. 6 constituted an insurrection. In my view, it was an attempt at a coup with various laws broken. It's interesting that we haven't had to consider this question with other candidates.
So here it is, 14th amendment Section 3:
No person shall be a Senator or Representative in Congress, or elector of President and Vice-President, or hold any office, civil or military, under the United States, or under any State, who, having previously taken an oath, as a member of Congress, or as an officer of the United States, or as a member of any State legislature, or as an executive or judicial officer of any State, to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof. But Congress may by a vote of two-thirds of each House, remove such disability.
There have been all kinds of arguments that this doesn't apply to the presidency. Also that isn't not enforceable, or only enforceable by the Supreme Court.
These are valid questions and there aren't loads of good answers because there isn't much case law on this. We really haven't had a lot of insurrections where we had to worry about barring the participants from office.
One thing that's at issue is how this provision is enforced since no enforcement mechanism is listed. I tried to find out about the enforcement and found very little. The most detailed is about a potential senator from NC named Zebulon Vance. He had been a representative, then joined the secessionists and was selected as senator after the war. He was barred per the 14th amendment and didn't try to serve, and eventually NC found a different candidate who passed per the 14th amendment.
It appears that officials had to present credentials, which could be rejected. After the Civil War, Congress refused to seat many senators and representatives from southern states. Pres. Johnson complained about this, and records show rejection of a GA senator.
Now the Colorado Supreme Court has blocked Trump from the primary there on the grounds of the 14th amendment Section 3. So this is strange, unprecedented for a candidate for president, but it is somewhat in keeping with a strict constructionist reading of the amendment.
Per the amendment, it applies to anyone who 1) "having taken an oath ... to support the Constitution of the United States, then 2) "engaged in insurrection or rebellion against the same." For those, "No person shall be a Senator or Representative in Congress, ... or hold any office, civil or military, under the United States..."
There's no requirement of a trial to determine it, so it's hard to say that Colorado isn't within its rights to bar him. Well, such interesting times we live in.