3 top witnesses I'd call in Trump impeachment trial and what I'd ask: Ex-US attorney

Barbara McQuade, Opinion columnist

The impeachment trial of President Donald Trump on abuse of power and obstruction of Congress charges may end without any witness testimony. If so, the Senate risks acquitting Trump without a full understanding of the facts. But facts, as they say, are stubborn things, and likely will trickle out over time, especially since former national security adviser John Bolton has a book deal and Ukraine fixer Lev Parnas is already talking on TV. A quick acquittal might not age well.

If the House managers are permitted to call witnesses, they no doubt would present many of the same people who testified during the impeachment inquiry — diplomats William Taylor and Gordon Sondland and other officials who described a scheme to withhold military aid and a White House meeting unless Ukraine announced (baseless) investigations into former Vice President Joe Biden and his son Hunter, who sat on the board of Burisma, a Ukrainian energy company, and Ukrainian interference in the 2016 U.S. presidential election (a debunked theory). But other witnesses, including some who were blocked by Trump during the House inquiry, are needed for a genuine quest for the truth.

It would be tempting to call Rudy Giuliani, Trump’s personal attorney, but his possible assertion of attorney-client privilege and his propensity to contradict himself make that strategy less than surefire. It might also be intriguing to call Trump himself, but, as the head of a coequal branch of government, he could not likely be compelled to appear, and no responsible lawyer would ever allow the famously mendacious president to testify under penalty of perjury.

Supreme Court Chief Justice John Roberts swears in senators for the impeachment trial of President Donald Trump on Jan. 16, 2020, in the Capitol in Washington.

One could also make the case for calling Vice President Mike Pence, who canceled his trip to Ukraine for the inauguration of President Volodymyr Zelensky in May. Did he cancel it because Ukraine had not announced the investigations, as alleged by Parnas, Giuliani’s indicted associate? Did someone direct Pence to change his plans? But implicating Pence might cause Senate Republicans to hesitate in convicting Trump, knowing that Nancy Pelosi, the Democratic House speaker, would be next in line for the presidency.

How to get the truth on Ukraine

Three other witnesses are essential to getting to the bottom of what happened in the Ukraine affair — Bolton, acting White House chief of staff Mick Mulvaney and Secretary of State Mike Pompeo. Because they have not been questioned, House managers would have to violate a prosecutor’s general rule to never ask a question to which they do not already know the answer. But sometimes risk is necessary for reward. These are the key questions these witnesses should be asked. 

Questions for all three witnesses:

►Were you aware of any request to any Ukrainian official to investigate Burisma, Hunter or Joe Biden or the role of Ukraine in interfering with the 2016 U.S. presidential election?

►If so, what was the role of President Trump in that request?

►Why was the Trump administration interested in investigating these matters?

►Did President Trump say he wanted these investigations to be completed, or was he simply interested in an announcement of the investigations to smear political rivals?

►Are you aware of a decision to withhold military aid from Ukraine in 2019?

►What was the reason that the aid was withheld?

►Who directed that the aid be withheld?

►Was the aid conditioned on Ukraine’s announcing the investigations?

►Who directed that the condition imposed?

►Did you find it to be in America’s best interest to withhold the aid?

Questions for John Bolton

►Why did you abruptly end a July meeting with Ukrainian officials when Sondland, the ambassador to the European Union, raised the topic of the investigations in exchange for a White House visit?

►Why did you direct National Security Council members Fiona Hill and Timothy Morrison to brief NSC lawyers about Ukraine developments?

►Did you make a reference to a “drug deal Sondland and Mulvaney are cooking up”? If so, what did you mean?

►Did you refer to Giuliani as a "hand grenade that is going to blow everybody up"? If so, why?

►Why did you resign from the Trump administration?

Questions for Mick Mulvaney 

►You stated at a news conference in October that the military aid was “absolutely” held up to get Ukraine to investigate the Democratic National Committee server that was compromised during the 2016 election, and then later that day issued a statement saying that the two things were not linked. Did someone suggest or direct that you walk back your first statement? If so, who?

►Did President Trump ever express a desire to block the House from conducting an effective investigation?

►Why did President Trump withhold witnesses and documents from House investigators?

►Did negotiations with Ukraine include the topic of dismissing criminal bribery charges against energy tycoon Dmytro Firtash, as alleged by Parnas?

Questions for Mike Pompeo 

►Why was it Giuliani, and not State Department officials, participating in conversations with Ukraine?

►Did you discuss with Giuliani the request for investigations and withholding of military aid?

►Please tell us about every conversation you have had with Giuliani about Ukraine.

►Sondland said you were aware that the investigations were a quid pro quo for a White House meeting and military aid. Is that true?

►Why was Ambassador Marie Yovanovitch recalled from Ukraine?

►Did you have concerns about her safety?

►Why did you refuse to issue a statement of support about her?

►In August, you exchanged email messages with Sondland regarding a proposed meeting between Trump and Zelensky to “break the logjam.” What did that language refer to?

►In August, you received a cable from Ambassador Taylor regarding the “folly” of withholding funds from Ukraine at a time when Russia was breathing down its neck. Why was his warning not heeded?

►Why did you block State Department employees from testifying before the House in the impeachment inquiry?

A trial featuring these witnesses and others, including former Energy Secretary Rick Perry and Michael Duffey, who handles national security programs at the Office of Management and Budget, could change the course of history. Or it could end the same way as the quick, cursory proceeding many Republicans seem to want — with the Senate falling short of the 67 votes needed to convict Trump and remove him from office.

Even so, at the very least Americans would have more information and a deeper sense of what’s at stake when they vote in November on whether to reelect this president.

Barbara McQuade, a former U.S. attorney for the Eastern District of Michigan, is a professor at the University of Michigan Law School, an NBC and MSNBC legal analyst, and a member of USA TODAY's Board of Contributors. Follow her on Twitter: @BarbMcQuade 

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This article originally appeared on USA TODAY: Trump impeachment trial: What I'd ask Bolton, Mulvaney and Pompeo