Rudy Giuliani responded to President Donald Trump's tweets on Monday asserting that he has the right to pardon himself and that the special counsel's investigation is unconstitutional.

Giuliani told Business Insider he believed Trump was "making it clear that he's not going to" pardon himself.

Of the notion that Mueller's appointment is unconstitutional, Giuliani said Trump was simply "throwing out an idea."

President Donald Trump's attorney Rudy Giuliani responded Monday to the president's assertions that he has the right to pardon himself and that the special counsel Robert Mueller's investigation is unconstitutional.

Trump started an early-morning firestorm when he claimed to "have the absolute right to PARDON myself" but said he had "done nothing wrong." The president insisted that "numerous legal scholars" agreed with his position, though the legal thinking on the issue is mixed at best.

No court has ruled on whether a president can pardon himself, though the Department of Justice wrote in a 1974 opinion, days before President Richard Nixon resigned in disgrace, that the president "cannot pardon himself."

In an interview with Business Insider, Giuliani said he believed the president was "making it clear that he's not going to" pardon himself.

"He doesn't have to do it, because he's done nothing wrong," Giuliani said. "If you just look at the Constitution, it says the president can pardon, and there are not words of limitation. Somebody could probably argue that there is a limitation, but it hasn't been decided by the court."

On Sunday, Giuliani said on NBC's "Meet the Press" that it would be "unthinkable" for Trump to pardon himself — but that it was something the president could "probably" do — because it would almost certainly lead to impeachment proceedings in Congress.

Giuliani also told The Huffington Post that Trump was basically immune from prosecution while in office, saying the president would have to be impeached before he could be indicted. As an example, Giuliani said Trump could've shot James Comey, whom Trump fired as FBI director last year, and still not be charged with a crime until after his impeachment.

"If a president pardoned himself, he would surely be impeached," Giuliani told Business Insider. "And that's the power. It's also the issue that's come up where I said if he shot somebody, he can't be indicted ... but he can be impeached and then indicted."

A New York Times report on Saturday detailed a 20-page memo to Mueller from Trump's lawyers — including John Dowd, who resigned in March from representing the president in the investigation — arguing that Trump, if he so wishes, could "terminate the inquiry, or even exercise his power to pardon."

Donald Trump. Getty Images

"I think the Dowd memo takes the most extreme position," Giuliani told Business Insider. "Some of it I'm not even sure I agree with completely. I agree with about 80% of it."

Giuliani said that if Mueller's team sought to compel Trump to sit down for an interview by issuing a subpoena, the president's legal team would take the battle to court and assert that the special counsel doesn't have that authority.

"Because they only have the authority given to them by the Justice Department, and the Justice Department has withheld the authority to indict the president or subpoena the president," Giuliani said.

Giuliani repeatedly cited a 2000 memo from the Justice Department's Office of Legal Counsel following President Bill Clinton's scandal, saying that while the Constitution does not give the president immunity from prosecution, the president cannot be indicted.

The federal statute governing the special counsel, meanwhile, says that they "shall comply with the rules, regulations, procedures, practices, and policies of the Department of Justice," though there is an exception for "extraordinary circumstances."

Pointing to the memo by Dowd, Giuliani said it should have mentioned the 2000 Justice Department memo.

Giuliani says the president is 'throwing out an idea'

Trump also tweeted on Monday that Mueller's appointment "is totally UNCONSTITUTIONAL!"

"Despite that, we play the game because I, unlike the Democrats, have done nothing wrong!" he continued.

That idea is undermined by a federal judge's ruling last month in a lawsuit filed by Paul Manafort, the former Trump campaign chairman. US District Judge Amy Berman Jackson dismissed that lawsuit and upheld the legality and scope of Mueller's investigation.

In response to Trump's tweet, Giuliani said he thought the president was "throwing out an idea."

"There are certain people who have argued ... that it is an illegitimate investigation," he said. "Now, if an illegitimate investigation of the president amounts to an unconstitutional one, I'd have to do more research on that."

Giuliani, the former New York mayor and US attorney, said that Trump "is not a lawyer" but that "he's got good instincts, and he's turned out to be right on most of this stuff."

"So I wouldn't dispute it with him, but that's not a legal opinion, like the OLC memo," he said.