During the Clinton administration there was a lot of talk about criminal prosecution of the President. Very few pundits or legal weasles stated that he could not be prosecuted while in office. In reality, until a prosecutor indicts a sitting President and the Supreme Court issues a ruling on the issue, the arguement is up in the air.
I would submit that if a sitting President can be ordered by the courts to submit to a legal deposition, then he can be ordered to stand trial. Either the courts have no ability to demand the President submit to anything, or they do have the ability to demand he submit as any citizen would. Clearly they have exhibited the ability to demand a President submit to their authority. So I submit the courts can and would allow an indictment if the situation warranted.
Robert Ray should have brought charges. Then the courts could have sorted the issue out. Asking the Justice Department under Janet Reno's leadership to make a ruling on that issue was incredibly stupid.