[mlo]

That is not what the phrase means. Illegals, visa overstays, tourists, all are under the jurisdiction of our law when they are here.

Diplomats with diplomatic immunity, soldiers of an invading army, these are not under the jurisdiction, and these are the persons to which that phrase refers. Because they are not under the jurisdiction of the law. Diplomats because they have immunity, soldiers because they operate under the laws of war.

[Ex gun maker.]

Funny how plain English can be construed so many ways.
Kind of like “Natural born citizen”, seems to come down to the interpretation of the person defining it.
I really doubt our founders intended that we have no control over who is a legitimate citizen.
In any case the current debacle cannot continue if we are to retain our “American” culture and values.