I'm pretty sure that he has immunity for any actions taken in his duties as president.
Yeah, he was throwing that around a few weeks ago. Someone wanted to sue him for something he said on the campaign trail, inciting violence against protesters or something.
His people insisted that he had immunity.
But it turns out that he only has immunity as president, for things he does as president. He's still subject to lawsuits, and I would assume arrests, for anything he did as a private citizen before he was inaugurated.