What are the criteria? Is there an explicit list? If there is a list, how robust is it in the face of changing times?
Before one takes an oath to defend the Constitution against enemies foreign and domestic, does one receive instruction on how to identify such an enemy?
If there is instruction, is it consistent across the different types of people who take such an oath?
What would a person have to do in order to be counted as an enemy of the Constitution?
Is there some kind of due process whereby one gets officially designated as such? Is there a body, an organ of the state responsible for this process or making this designation?
If evidence is required, what is the bar that needs to be met?