A couple thoughts on the Special Master situation.
It seems to me several issues in this case are being conflated in the court filings and in the recent court opinion.
One of the primary issues is Trump's assertion of executive privilege. A second is ownership of the documents that were retrieved from Mar-a-Lago. A third is the Presidential Records Act (PRA).
Trump is asserting that he can assert executive privilege against the execute branch itself. In a sense, he is asserting that the documents were protected by executive privilege "at birth" while he was president, and he is the only person that can waive it, even though he is now a private citizen.
This is a bit odd on the face of it, because Trump is a private citizen, so what gives him the power to invoke executive privilege against the executive branch itself? Unfortunately, this is not quite as clear as it might appear because the Supreme Court in Nixon v. Administrator of General Services did state in dictum that a former president does potentially retain some limited executive privilege:
www.law.cornell.edu
To my mind it would be absurd for a court to conclude that a former president could assert executive privilege with regards to classified documents and thereby prevent a current administration from having access to the documents. These documents are prepared by employees of the executive branch to enable the executive branch to carry out the responsibilities of the executive branch. The dictum in the Nixon case appears to be there because the court didn't want to make an across-the-board ruling that executive privilege cannot be applied against the executive branch itself, even though the court held that executive privilege didn't apply to the documents at issue in that case. I have not researched this issue, but I'm not aware of a single case in which a court upheld a claim of executive privilege by a former president against the executive branch when the executive branch waived the privilege. Thus, even for non-classified documents, an assertion of executive privilege strikes me as being extremely weak.
A practical problem with appointing a special master to determine what is covered by executive privilege is that there is no law defining what would be protected by it. Every court case I'm aware of ha held that, in so many words "We don't know what (if anything) might be covered by executive privilege, but we do not that the documents at issue in this case are not covered by executive privilege." In theory, a special master might be able to put some documents that are not covered in one pile, and create another pile of documents that are "unknown" because the documents are not similar to any other prior cases involving executive privilege.
In terms of privilege vs ownership, these are separate issues but the court seems to be conflating them (Trump's lawyers are doing their best to conflate them). A successful assertion of a privilege means that the information (evidence) cannot be entered at trial. For example, if my lawyer decides to communicate with me by writing on a government-owned vehicle, and I take a picture of the writing on the vehicle, I might be able to keep the content of the writing from being entered as evidence at trial on the basis that the information is attorney-client privileged. However, that does not mean that I now own the government's vehicle. In other words, even if Trump is successful in keeping the
contents of some of the documents from being used as evidence, it doesn't mean he
owns the documents themselves or the information in the documents.
By way of example, if a former president walked out of the White House with detailed plans for a top secret aircraft that required billions of taxpayer dollars to develop, does anyone think the former president could auction off the plans to the highest bidder, domestic or foreign?
There also seems to be some confusion about how the PRA fits in. A lot of the discussion seems to be based on the notion that the PRA somehow supersedes the other federal laws dealing with defense information, concealing evidence, etc. I can't see how this could be true. The PRA does not purport to grant former presidents immunity to other laws.
The PRA does give a former president some discretion to retain personal documents. Again, I can't see how this would supersede other laws. If a president stole a car while president and he made a written record of it, he could very well assert that this document is personal and he's therefore not required to turn it over under the PRA. However, this would not mean that the document could not be seized during a law enforcement investigation into the stolen car. The PRA does not create some sort of super-duper ownership/immunity law that protects former presidents from all other laws.
At the risk of creating a straw man, Trump's lawyers seem to be arguing that a former president can take any documents he wants with him after he leaves office, and this private citizen somehow has special powers and privileges to do anything he wants with these documents (and any information in the documents), and everyone else on the planet is powerless to do anything about it. No law or court case says anything remotely similar to this, but Trump's lawyers seem to be "all in" at this point because they really do not have anything else.
And that's my huge opinion.