Even if the Congress specifies procedures for classification and declassification and procedures for clearances, are the President and VP subject to such procedures? Isn't that a violation of the separation of powers? The absurdity is manifest: this would imply the bureaucrats could deny a President a clearance and therefore deny him the ability to know what executive departments nominally under his authority are doing.
Smith has to argue that as soon as Trump left office with docs he just read, he violated the law, something for which there is no precedent and which stinks like selective prosecution.
Congress does not classify or declassify documents. It authorizes the Executive Branch to do these things. By definition, the President of the United States (the only Executive Branch official named in the U.S. Constitution who has defined Executive Branch powers) has plenary authority over the entire Executive Branch and has the sole discretion to accept or override any such decision related to classifying or declassifying documents.