"If this sounds like legal theorizing, just consider the fact that Mr. Trump’s position is soundly contradicted by the Richard Nixon case. Under Mr. Trump’s view, Nixon would not have been guilty of obstruction for ordering the F.B.I. to stand down on the investigation of the Watergate burglars or paying off the defendants to keep them quiet.
Subsequent investigations into alleged abuses of presidential power — Iran-contra as well as Whitewater — took it as accepted law that the president is capable of obstructing justice. And while the case of the president can present challenging legal and practical questions of enforcement, both because the president is the head of the executive branch and because of the political levers he can pull, there is scant support among constitutional scholars or in the case law for the president’s drastic argument.
The second pillar of the letter submitted by Mr. Trump’s lawyers to Mr. Mueller is that he is too busy running the country to sit for an interview. Relatedly, they argue, forcing him to testify “demeans the office of the president before the world.”
Here Mr. Trump’s position run completely afoul of another presidential precedent: that of Bill Clinton. Mr. Clinton argued to the Supreme Court that the demands of sitting for a deposition in the Paula Jones case would leave him unable to discharge satisfactorily his unique constitutional responsibilities. The Supreme Court rejected the argument unanimously, and Mr. Clinton was forced to testify, initiating an indecorous process that led to his impeachment."