Eric Foner, one of the most eminent historians of the Reconstruction period, argues that Trump should be disqualified because he “took an oath to support the Constitution and now he has given aid to insurrection and that is the kind of thing the people who wrote the 14th Amendment were trying to avoid” (Emphasis added). But aid, too, is carefully limited by the text — and the way in which it is used offers further reason not to read the term “engaged” to cover conduct that would render the rest of Section 3’s definition superfluous.

Having sidestepped liability for merely secondary participants in the “engaged in” portion of Section 3, its framers used well-known language to cover such participants separately, referring to them as those who have “given aid and comfort to the enemies” of the United States. This was a phrase with long and specific history in the law, already used in the definition of “treason” in Article III, Section 3 of the Constitution. “Aid and comfort” is unquestionably a broader term than “engage,” and would extend to statements of encouragement — a definition that the Worthy and Brown cases clearly considered. It was the “aid and comfort” provision of Section 3 that was used against Victor Berger, the Wisconsin socialist who vocally opposed the war effort during the First World War.

As in the Article III definition of treason, however, the key word is “enemies”: An enemy does not exist until hostilities are declared or commenced. Prior to the Civil War, it was limited to foreign enemies in an actual or declared war. The Supreme Court, in Prize Cases, extended its use for purposes of wartime maritime law to include the Confederacy, which obviously claimed to be a sovereign government. Even if we assume (sensibly) that the broader definition should be used, “enemies” signifies something much more like a real government engaged in a real war than an ad hoc mob that forms, riots, and dissipates in the course of an afternoon.