I was looking up the presidential records act and from what I'm reading it looks like the documents are the government's property not his. However, I have a little reading comprehension issues so I could be (and hopefully I am) wrong. I don't know much about legal stuff either I admit. I also wasn't sure if he could testify at his own trial.
Trump: 'I'm Allowed to Do Whatever I Want' With Classified Info
Donald Trump said he "absolutely" plans to testify in the classified documents legal case, telling Hugh Hewitt, "I'm allowed to do everything I did."
www.google.com
The Presidential Records Act | National Archives
www.archives.gov