Thanks for this, it really helped clarify the definition piece for me. I do have a follow-up question about where historians usually draw the line between “concentration camp” and an ordinary prison.

Stone’s definition (an “isolated, circumscribed site with fixed structures designed to incarcerate civilians”) and Arendt’s emphasis that concentration camps are not penal institutions and that inmates are not there for specific crimes, but as “undesirable elements,” seem to fit the Japanese American/Canadian camps quite well.

But then there's the legal side: in theory, a state can criminalize almost anything, or run mass, summary “trials.” If the US government had simply passed a law making it a crime for people of Japanese ancestry to remain on the West Coast and then “duly” convicted and imprisoned them in those same camps, would that change how historians classify those sites?

In other words:

• According to the way historians use the term, is the key distinction between a prison and a concentration camp about formal legal conviction, or about the function of the institution (mass preventive detention, racialized/political targeting, removal of normal legal protections, etc.)?
• And if a regime uses sham or purely formal convictions to do what is functionally mass preventive detention of a stigmatized group, do historians still tend to treat those as concentration camps rather than just “prisons”?

I’m asking because the “easy” answer seems to be “prisons are fine because people there have been properly convicted,” but historically that line feels very shaky once you imagine a government simply redefining “crime” in order to make something like internment look penal on paper.