Donald Trump’s lawyers sent a private 20-page letter to the special counsel Robert Mueller to assert that he cannot be forced to testify in the investigation into Russian meddling in the 2016 presidential election.

Donald Trump’s lawyers  also argue that Trump could not have committed obstruction of justice because he has absolute authority over all federal investigations.

The existence of the letter sent in January was reported on Saturday by the New York Times which posted a copy of the memo  online. 

The memo is an assertion of presidential power and another front on which Trump’s lawyers have argued that he cannot be subpoenaed.

In the letter, the legal team argues that a charge of illegal obstruction is moot because the US constitution empowers the president to, “if he wished, terminate the inquiry, or even exercise his power to pardon”. 

In the letter, according to the New York Times, the president’s legal team write: “It is our understanding that the reason behind the request for the interview is to allow the special counsel’s office to complete its report.

“After reviewing the list of topics you presented, it is abundantly clear ... that all of the answers to your inquiries are contained in the exhibits and testimony that have already been voluntarily provided to you .... all of which clearly show that there was no collusion with Russia, and that no FBI investigation was or even could have been obstructed.

“It remains our position that the president’s actions here, by virtue of his position as the chief law enforcement officer, could neither constitutionally nor legally constitute obstruction because that would amount to him obstructing himself, and that he could, if he wished, terminate the inquiry, or even exercise his power to pardon if he so desired.”

The memo goes on to say that the investigation has had the cooperation and backing of the president and White House despite it remaining a “burden” on him and the administration.