Could Comey's testimony lead to impeachment?

Former FBI director James Comey has accused President Donald Trump of lying and defaming him in three hours of testimony before the Senate Intelligence Committee Comey. Mr Comey said he had no doubt he was fired from the FBI due to his investigation into Russian meddling with the US election. However Mr Comey stopped short of saying the president obstructed justice and agreed that Mr Trump did have the authority to ask him to stop investigating Flynn. Kathryn Ryan speaks to Harvard law professor Alan Dershowitz.