The former acting Solicitor General of the United States blasted President Donald Trump's legal strategy during the impeachment inquiry.
CNN's Anderson Cooper interviewed Neal Katyal about his new book, Impeach: The Case Against Donald Trump.
"What do you make of the White House strategy, A., its effectiveness and, B., legality, in terms of not cooperating at all, no documents from the State Department, from the White House other than that rough transcript which they released early on," Cooper said.
"I dedicated my life to the study of the constitution and I didn't know that the president's strategy here was a thing," Katyal replied. "I didn't think it was possible."
"I mean, the idea that a president on his own can unilaterally say, 'I'm not going to bother cooperating with an impeachment investigation' -- that is the essence of constitutional arrogance and the destruction of our separation of powers," he explained.
"I think it is an impeachable offense just the way the president has acted toward this impeachment investigation," he added.