The memo to special counsel Robert Mueller said the president couldn't have obstructed justice because he has full authority over federal investigations and could even end the Russian Federation probe, the New York Times reports.
It remains unclear what, if any, information Trump based his claim on, but it fits into his and his administration's efforts to discredit Mueller's probe, which the president has consistently derided as a "witch hunt".
For many months after Mueller's appointment previous year, Trump avoided directly challenging the special counsel.
The president commented on the issue after his lawyer, former Mayor Rudy Giuliani, asserted that Trump had the executive privilege to pardon himself.
"They can't emotionally come to grips with the fact that this whole thing of Russian collusion didn't happen, (and) they are trying to invent theories of obstruction of justice", said Giuliani, a former NY mayor, referring to Mueller's team.
He said Mr Trump's tough line had forced North Korean leader Kim Jong Un to plead to reschedule their summit.
He also played down the possibility that Trump could pardon himself, suggesting he might have that authority but would be unwise to use it. "If he shot James Comey, he'd be impeached the next day", he said.
"Your office clearly lacks the requisite need to personally interview the president", it said. "I know this one: It's because if you bring the grain over the river first, the fox will collude with the Russians to get the chicken".
Other experts made the same point, while others said the memo went too far.
Additionally, Marcus thinks that Mueller will want to lay down a marker that presidents can not avoid facing justice if they yell about "deep state" conspiracies for so long that prosecutors just give up out of exasperation. "President Trump is not going to do that".
No court has ruled on whether a president can pardon himself, though the Department of Justice wrote in a 1974 opinion, days before former President Richard Nixon resigned in disgrace, that the president "cannot pardon himself".
"We had Repeal & Replace done (and the saving to our country of one trillion dollars) except for one person, but it is getting done anyway". So presidents can pardon federal offenses, but not state ones.
- Apple announces anti-addiction features for iPhones
- Microsoft to take on Amazon with $7.5 billion GitHub deal
- Meeting with Kim Jong Un will go on as scheduled
- The 6 Biggest New iPhone Features Apple Just Announced
- California primary election, San Diego County races, when to expect results
- What Analysts are hoping about Apple Inc. (NASDAQ:AAPL)'s WWDC event?
- Israel has carried out air strikes on Hamas sites
- IOS 12 introduces new features to reduce interruptions and manage Screen Time
- Trudeau says tariffs on steel and aluminum are 'insulting'
- Apple's software improvements could make AR as universal as iOS