Michael Zeldin, a CNN legal analyst, served as deputy independent counsel, and later as independent counsel, in the investigation into allegations that the administration of George H. W. Bush violated the privacy rights of candidate Bill Clinton in the 1992 presidential campaign. He also served as a special counsel to Robert Mueller in the Department of Justice. The opinions expressed in this commentary are those of the authors; view more opinion articles on CNN.

(CNN) I have spent the last week glued to the impeachment trial on TV, watching and listening carefully to the presentations of the House managers and President Donald Trump's defense lawyers.

Two things struck me as crystal clear: First, although one might disagree with the arguments being made, each side was represented by very capable advocates. Second, each team mostly spoke to their side of the aisle; they seemed to have no real expectation that the other side would consider their views. As Paul Simon sang in "The Boxer ," "a man hears what he wants to hear and disregards the rest." The same is probably true of the American public.

That said, I think that overall, the House managers made the stronger case.

Article One: Abuse of power

Although President Zelensky assured President Trump that he would be very serious in looking into the case, when the investigation did not appear to be moving forward, President Trump withheld congressionally authorized military aid to Ukraine and a president-to-president White House meeting.

I believe that the House managers effectively made the case that President Trump improperly demanded the Biden investigation for his personal political advantage, and not to further the United States' national security interests. In my view, Trump's initial demand and his subsequent withholding of aid to Ukraine until President Zelensky publicly announced the investigation of the Bidens constituted an abuse of the powers of his office.

As the House managers demonstrated through their dissection of the July 25, 2019, call summary, Trump told Zelensky that he wanted a favor and that he expected an investigation because "the United States has been very, very good to Ukraine. I wouldn't say it's reciprocal..."

The President's request was confirmed by multiple witnesses, most notably David Holmes, who overheard the President specially ask about the status of the investigation on his call with US Ambassador to the European Union Gordon Sondland soon after Sondland met with the Ukrainians in Kiev to discuss the matter.

Instead of fully responding to the impropriety of the initial ask by Trump on the July 25 call, President Trump's lawyers focused primarily on the secondary issue -- whether the President improperly withheld military aid when the announcement of the investigation was not immediately forthcoming (the so-called quid pro quo), and the lack of direct evidence to support the accusation.

Leaving aside the revelation by former national security adviser John Bolton that the President told him personally that there was a direct link between the freezing of military aid to Ukraine and the sought-after investigation of the Bidens, and the testimony of State Department officials, such as Bill Taylor, who called the withholding of military aid "crazy," the Trump lawyers failed to adequately rebut the primary assertion that the "ask" for the Biden investigation was an abuse of power because it was made with the corrupt purpose of aiding Trump's reelection efforts.

Article Two: Obstruction of Congress

Article Two, obstruction of Congress, is predicated on the President's blanket refusal to cooperate in any meaningful way with the House investigations.

Which side made the better case is a close call. I see the equities on both sides. I believe, however, that when viewed in its entirety, the complete record of the President's response through his counsel and in the public domain (Twitter, campaign rallies and press statements) reflects a complete unwillingness to cooperate well beyond the position articulated in the trial by deputy White House counsel Patrick Philbin.

The House, exercising its sole power of impeachment, as well as its general investigatory authority, properly issued multiple subpoenas with 71 individualized requests for records in the possession or control of the White House, the Office of the Vice President, the Office of Management and Budget, the Department of State, the Department of Defense or the Department of Energy.

It did so pursuant to the rules of the 116th Congress and House Resolution 660 directing three House Committees (Intelligence, Foreign Affairs and Oversight) to "continue their ongoing investigations as part of the existing House of Representatives inquiry into whether sufficient grounds exist for the House of Representative to exercise its Constitutional power to impeach [President] Trump."

In response to the House subpoenas for witnesses and documents, White House counsel Pat Cipollone advised Speaker Nancy Pelosi in an October 8, 2019, letter that, because the House investigation lacks any legitimate constitutional foundation, any pretense of fairness, or even the most elementary due process protections, the Executive Branch cannot be expected to participate in it. Executive Branch agencies reaffirmed that it was the position of the President to refuse to comply with subpoenas issued for documents.

The outcome of this directive was that the Office of Management and Budget, the Department of State, the Department of Energy and the Department of Defense refused to produce any documents or witness testimony.

Philbin elaborated that the position of the President not to cooperate wholesale with the House investigation was grounded in well-established separation of powers concepts that the Executive Branch enjoyed absolute immunity and that the requested documents potentially could implicate executive privilege. (It is noteworthy that, typically, claims of executive privilege fail if asserted to conceal wrongdoing.)

According to Philbin, if Congress believed that the subpoenas were authorized, the House should have gone to court to enforce them.

But this argument rings hollow, given the President's position that the courts have no jurisdiction to resolve this conflict.

It also invites the question: If the President believed that the subpoenas were constitutionally defective, why didn't he go to court to quash them, as is typical in litigation throughout the country?

In the end, it became clear that the House could not rely on the President to comply with their requests given his overly broad interpretation of privilege, his belligerence and White House counsel's unwillingness to cooperate in good faith.

Indeed, the President's obstructive conduct continues to this day with the Trump administration's improper redaction of emails detailing how Department of Defense and the White House Office of Management and Budget officials reacted to President Trump's decision to halt military aid to Ukraine ordered to be released in response to Freedom of Information Act litigation, the President's announcement that he would seek to enjoin publication of certain aspects of John Bolton's forthcoming book , and Trump lawyer Alan Dershowitz's outlandish position on the Senate floor that if a President thinks that his reelection is in the national interest, any actions that he takes toward that end cannot, by definition, be impeachable

Consequently, Trump left the House with no choice but to proceed as it did with the second article of impeachment.

In my view, the House managers were more persuasive in arguing that, if the President is able to declare the circumstances under which he will cooperate with Congress and he can refuse unilaterally to cooperate when his conditions are not met, the House's investigatory powers would be null and void. This is not a tenable outcome.

Is a crime required?

Constitutional lawyer Alan Dershowitz and former independent counsel Robert Ray argued that, even if all the facts were accepted as true, the articles of impeachment would be defective because they do not allege a criminal offense.

In their view, abusive conduct and an interbranch dispute over witnesses and documents does not meet the constitutional standard of a high crime and misdemeanor. During the House Judiciary Committee hearing, constitutional law experts Noah Feldman, Pamela Karlan and Michael Gerhardt disputed the Dershowitz/Ray position, arguing that impeachable conduct does not have to constitute a crime

According to those experts, "offenses," which is the word used by Alexander Hamilton in the Federalist Papers, relates to the misconduct of public officials in violation or abuse of the public trust -- irrespective of whether a crime is committed. This view is consistent with the overwhelming weight of authority and is widely held by constitutional scholars. The Dershowitz/Ray position is a constitutional outlier.

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In my view, the late Charles L. Black Jr., Sterling Professor Emeritus of Law at Yale Law School, best articulates the appropriate standard for evaluating what meets the definition of high crimes and misdemeanors in the constitutional sense: That is, offenses that are clearly wrong, even if not criminal, and in Black's words, "seriously threaten the order or political society as to make pestilent and dangerous the continuance in power of their perpetrator."

President Trump's alleged conduct -- in soliciting Ukraine to investigate his political rival and, then, in withholding military aid until the investigation is publicly announced-- violates the public trust and renders his continuation in office a danger to the Constitution. His obstruction of Congress compounds the offense.

Witnesses

If the Senate does not call Bolton and the other witnesses who have firsthand knowledge of the President's actions, it would be facilitating a cover-up

The Senate needs to perform its constitutional duty to hold a full and fair trial in which all relevant witnesses testify under oath and all pertinent documentary evidence is disclosed irrespective of whether the House was unsuccessful in obtaining these witnesses and documentary evidence. To do otherwise is to set the dangerous historical precedent that full and fair Senate impeachment trials are not constitutionally required.