CNN's Jake Tapper asked Giuliani if presidential obstruction of justice is possible. Giuliani said it might involve a gun.

In an interview with President Trump's personal attorney, Rudy Giuliani, on Sunday, CNN's Jake Tapper sought to get to the bottom of what President Trump did or did not say to fired FBI Director James Comey about the investigation of former National Security Adviser Gen. Michael Flynn. But Tapper aimed at bigger topics, too.

"Let me ask you a larger philosophical question," he asked Giuliani. "For the record: Do you think that a president of the United States, any president, can ever obstruct justice? Or do you think that's impossible, because the president's the executive in charge of the Justice Department?"

"There are people who argue that he could never obstruct justice. I think that’s too far-fetched an argument and we don’t have to make it," Giuliani said. "I mean, suppose the president put a gun to someone's head and said, 'I'm going to kill you unless you stop testifying or don't testify.' Obviously, I can't imagine that that isn't an obstruction of justice."

"I think now," Giuliani continued, "our argument is that when he's exercising his power as president — obviously using a gun is not exercising his power as president — and he's firing somebody, then it becomes very, very questionable whether it can be an obstruction of justice."

Before Giuliani joined Trump's legal team, the president's attorneys sent a letter to Special Counsel Robert Mueller arguing Trump can "terminate [Mueller's] inquiry, or even exercise his power to pardon" its targets, and any actions he takes cannot "constitute obstruction because that would amount to him obstructing himself."

Watch the full interview below. The obstruction discussion begins shortly before the five-minute mark.