I am assuming the authenticity of the questions that Special Counsel Robert Mueller reportedly wants to ask President Trump. The questions indicate that, after a year of his own investigation and two years of FBI investigation, the prosecutor lacks evidence of a crime. Yet he seeks to probe the chief executive’s motives and thought processes regarding exercises of presidential power that were lawful, regardless of one’s view of their wisdom.

If Bob Mueller wants that kind of control over the executive branch, he should run for president. Otherwise, he is an inferior executive official who has been given a limited license — ultimately, by the chief executive — to investigate crime. If he doesn’t have an obvious crime, he has no business inventing one, much less probing his superior’s judgment. He should stand down.

The questions, reported by the New York Times, underscore that the special counsel is a pernicious institution. Trump should decline the interview. More to the point, the Justice Department should not permit Mueller to seek to interrogate the president on so paltry and presumptuous a showing.