The Dispatch quoted Mike Davis of the Article III project who had an interesting thought on the matter.
As much as the media wants this to be about classified documents, because of the irony of the guy who decried Hillary's server potentially mishandling classified info himself, it's probably not about that.
As President, Trump could declassify stuff at will. So if he took stuff away that was still classified, before noon on January 20, then it's not so much that he did something he's not allowed to do, as it is he forgot to file the proper paperwork before doing something that he is allowed to do. Technically a crime, but not one worth punishing.
So the fact that some of these documents may have been classified is probably not material to the case that the FBI is trying to build.

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