President Trump’s pick for attorney general sent the Justice Department an unsolicited memo earlier this year questioning the appropriateness of an obstruction probe special counsel Robert Mueller is said to be conducting of certain Trump actions in the White House.

The memo, first reported by the Wall Street Journal, was sent to the Department in June 2018 by William Barr, who previously served as Attorney General under President George H.W. Bush and can be read in full below.

Barr in the memo acknowledged that he was basing his assessment on what had been publicly reported about Mueller’s investigation and he recognized that he was “in the dark about many facts.” However, he argued that Mueller “should not be permitted to demand that the President submit to interrogation about alleged obstruction.”

The memo called Mueller’s obstruction theory “fatally misconceived” and as Barr understood it, premised on “a novel and legally insupportable reading of the law.”

The nearly 19-page memo suggested that, while there are certainly examples of obstructive conduct that could be investigated — destroying or altering evidence, suborning perjury, inducing witnesses to change testimony — President Trump, as far as Barr knew, wasn’t being “accused of engaging in any wrongful act of evidence impairment.”

The memo argued that Mueller was pushing an “unprecedented expansion of obstruction law” so that it reaches actions President Trump took that were within the “discretion vested in him by the Constitution.”

Barr warned that such a theory could have “potentially disastrous implications” for both the Presidency and the entire executive branch.

Barr said Mueller’s obstruction theory claims that he can investigate for a corrupt motive Presidential actions that on their face are within a President’s discretion.

“It is hard to imagine a more invasive approach encroachment on Executive Authority,” Barr wrote.