This could go to the Supreme Court and delay the investigation. Does Trump think that's a good thing for him?
And in case you missed the list of 49 questions: Mueller Has Dozens of Inquiries for Trump in Broad Quest on Russia Ties and Obstruction. So of course Donald Trump went on Twitter and complained about the list having been leaked, and we now know that the list (in its published form) was compiled by his own lawyer.
Trump to Add Clinton Impeachment Lawyer Emmet Flood to Replace Ty Cobb, and the day is still young.