The Special Prosecutor’s proposal to interview President Trump would violate executive privilege. Executive privilege has been asserted in one form or another for over two centuries by Presidents including Washington, Jefferson, Jackson, Nixon, Reagan, Clinton, Bush, and Obama.
Like many privileges, the executive privilege is a qualified privilege and the touchstone is substantial need. Mere probable cause does not suffice. In cases involving testimony, the President and his staff generally prevail, but subpoenas duces tecum (requiring production of documents or physical evidence) are generally enforced allowing investigators to obtain this nontestimonial evidence. The physical act of providing evidence is less burdensome than the indignity of questioning.
Persons enjoying legal privileges are again reminded that an investigator with a subpoena is an adversary intent on incriminating the recipient and not merely a “public servant” trying to “clear things up so we can move on.”