History will be made later when Donald Trump becomes the first former US president to appear in court on federal criminal charges.
He's due to be indicted on 37 charges when he appears in court in Miami later.
He denies accusations he collected classified documents and refused to give them back after leaving the White House.
He insists he's innocent and that the case is a hoax.
The files allegedly contained information on nuclear programmes, and some were stored in the bathroom of his Florida estate.
Richard Painter, who was the chief ethics adviser to President George W Bush, says Donald Trump's actions weren't properly challenged during his time in office.
"He did obstruct justice in the Russia investigation, but he was the sitting president, so the Department of Justice was not willing to indict him.
"If they had then a lot of the other things that happened might not have happened. But he got the message that he could do whatever he wanted".
