Morrison was among the people listening in on the July 25, 2019 phone conversation between
President Trump and
Ukrainian president Volodymyr Zelensky that is central to the
impeachment inquiry against Donald Trump. He was a primary source of information regarding the matter to
William B. Taylor, Jr., the acting
US ambassador to
Ukraine. Morrison's deposition in the impeachment inquiry against Donald Trump, given behind closed doors on October 31, partially corroborated the earlier deposition by Taylor, in particular that U.S. Ambassador to the E.U.
Gordon Sondland had told , an aide to Zelensky via telephone that military aid to Ukraine, and a White house meeting with Trump, were conditional on a Ukrainian public announcement of an investigation into Burisma, and the Ukraine involvement in the 2016 U.S. presidential election. Morrison also testified that his concerns regarding the Trump–Zelensky call, which he promptly communicated to White House lawyers, were about repercussions if the transcript of the call was to be leaked, not about the legality of its content or
quid pro quo. According to official transcripts of Morrison's closed door testimony, Morrison stated, "I want to be clear, I was not concerned that anything illegal was discussed," in the telephone call between Trump and Zelensky. During public testimony before the U.S. House of Representatives on November 19, 2019, Morrison stated that Sondland confirmed to him that there was indeed a
quid pro quo requirement for US aid to Ukraine, and again brought up the telephone conversation between Sondland and Yermak, which took place on September 1, 2019. ==Subsequent career==