- Three of the scholars who testified, each invited by the committee's Democrats, said they believed the evidence gathered so far by investigators showed that Trump was guilty of impeachable offenses.
- A fourth, invited by committee Republicans, dissented, arguing that the investigation fell short, at least so far, of the high bar set by the Constitution.
The historic impeachment battle in the House of Representatives entered a new phase on Wednesday, as four of the nation's top constitutional law professors testified about whether President Donald Trump should face a trial in the Senate.
Three of the scholars who testified, each invited by the committee's Democrats, said they believed the evidence gathered so far by investigators showed that Trump was guilty of impeachable offenses. A fourth, invited by committee Republicans, dissented, arguing that the investigation fell short, at least so far, of the high bar set by the Constitution.
The professors who supported impeachment are Noah Feldman of Harvard University, Pamela Karlan of Stanford University, and Michael Gerhardt of the University of North Carolina. George Washington University's Jonathan Turley opposed impeachment.
The testimony on Wednesday was largely technical, focusing on the historical debates over whether to include a provision for the removal of the president in the nation's founding documents and punctuated at times by Republican attempts to delay using procedural motions.
But at points the testimony of the scholars grew heated as the stakes of the debate came to the fore.
"If what we are talking about is not impeachable, then nothing is impeachable," Gerhardt said during the hearing.
Turley, on the other hand, said that if the House votes to impeach Trump for obstruction, it would be those lawmakers, and not Trump, who were guilty of abusing power.
"You are doing exactly what you're criticizing the president of doing," said Turley, who said in a detailed 53-page opening statement that he did not support Trump politically and voted for Presidents Barack Obama and Bill Clinton in the past.
The hearing followed the public testimony of a dozen witnesses before the House Intelligence Committee in recent weeks. That committee, led by Democratic Rep. Adam Schiff of California, sent a 300-page report to the judiciary panel on Tuesday.
The report accuses Trump of undermining the national interest of the United States by pressuring the president of Ukraine to open investigations into former Vice President Joe Biden, including by withholding a White House meeting and nearly $400 million in security assistance.
The arguments in favor of impeachment focused heavily on the views expressed by the nation's founders.
"Some day we will no longer be alive, and we will go wherever it is we go, the good place or the other place, and we may meet there Madison and Hamilton," Feldman said during his testimony.
"And they will ask us, when the president of the United States acted to corrupt the structure of the Republic, what did you do?" he said. "And our answer to that question must be that we followed the guidance of the Framers."
Feldman said that based on the available evidence, Trump had committed "precisely" the type of infraction that the Framers viewed as impeachable during the late 18th century.
The scholars who said the evidence supports impeachment laid out a case that Trump could be guilty of bribery, which is explicitly named as an impeachable offense in the Constitution, as well as obstruction of justice and abuse of power, which were included in the articles of impeachment approved by the judiciary committee in the case of former President Richard Nixon.
One of the central disputes in the hearing was whether the Constitution requires the president to be guilty of violating specific criminal laws in order to be impeached. Turley argued that if the House intends to impeach Trump for crimes that have modern day definitions, they should have to prove that he is guilty of the crime as it is now understood.
"I've gone through all of the crimes mentioned. They do not meet any reasonable interpretation of those crimes, and I'm relying on express statements from the federal courts," Turley said.
"You're trying to remove a duly elected president of the United States," he said. "It's unfair to accuse someone of a crime, and when others say, well, those interpretations you are using to define the crime are not valid, to say they don't have to be valid, because this is impeachment."
But the other professors rejected that argument.
"Impeachable offenses do not have to be criminal offenses, as you well know," Gerhardt told lawmakers. "And so what we are talking about is an abuse of power. An abuse of power that only the president can commit."
Feldman said that while federal statutes define bribery, "they can't defeat what's in the Constitution."
"If the House believes the president solicited something of value in the form of investigations or an announcement of investigations, and that he did so corruptly for personal gain, then that would constitute bribery under the meaning of the Constitution. And it would not be lawless. It would be bribery under the law."
Karlan, for her part, wielded a digital copy of Samuel Johnson's 18th century dictionary — commonly cited in constitutional cases — which she said defines bribery as the giving or taking of rewards for bad practices.
"So if you think it's a bad practice to deny military appropriations to an ally that have been given to them, if you think it's bad practice not to hold a meeting to buck up the legitimacy of a government that's on the front line, and you do that in return for the reward of getting help with your reelection, that's Samuel Johnson's definition of bribery," she said.
If the House impeaches Trump on those grounds, it'll set a dangerous new precedent, Turley argued. He said that in the impeachment cases against Nixon and former President Bill Clinton, no one disagreed that the alleged offenses constituted crimes.
"Those were not just proven crimes, they were accepted crimes," he said. "That is, even the Democrats on the judiciary committee agreed that Bill Clinton had committed perjury."
The professors were similarly divided over the crime of obstruction of justice. Democrats have said that Trump has obstructed their inquiry by ordering officials not to assist in the investigation, including by defying subpoenas, some of which have now become subject to court challenges.
This, Gerhardt said, was an "east, straightforward" issue. "The subpoenas that have been issued of course are lawful orders."
"I don't think it's possible to emphasize this strongly enough. A president who will not cooperate with an impeachment inquiry is putting himself above the law," Feldman said. "Putting yourself above the law as president is the core of an impeachable offense. If a president could not be impeached for that, he would in fact not be responsible to anybody."
But Turley said that obstruction "is a crime also with meaning," rather than an abstract element of abuse of power.
"President Trump has gone to the courts. He is allowed to do that. We have three branches, not two," Turley said.
Gerhardt fired back that obstruction of justice was not limited to the courts.
"Obviously here, there are judicial proceedings going on," he said. "But there is also a really critical congressional proceeding, which brings us to obstruction of Congress."
"There's never been anything like the president's refusal to comply with subpoenas from this body," Gerhardt said.
The Judiciary Committee, which is led by Democratic Rep. Jerry Nadler of New York, has not yet drafted articles of impeachment. If it drafts and approves any, they will move to the full House of Representatives.
It requires a majority vote of the Democratic-led House to impeach, after which it would take two-thirds of the Republican-led Senate to remove Trump from office. So far, none of the Senate's 53 Republicans have suggested that they will vote to remove him.