The House Judiciary Committee has revealed the four constitutional law scholars who will kick off that panel's handling of the House's impeachment inquiry against President Donald Trump.

Stanford Law School's Pamela Karlan, Harvard Law School's Noah Feldman, Michael Gerhardt from the University of North Carolina School of Law, and Jonathan Turley, of the George Washington University Law School, will all be testifying at Wednesday's hearing.

The hearing is titled "The Impeachment Inquiry into President Donald J. Trump: Constitutional Grounds for Presidential Impeachment."

Several of the witnesses are no stranger to congressional testimony, as they have played the role of expert voices during prior hearings on Capitol Hill. However, the stakes are sure to be demonstrably higher Wednesday, in the midst of an impeachment proceeding that has already proven to be contentious and highly partisan.

Here's what you need to know about each of the witnesses who will help lay the groundwork for the next phase of the House's impeachment inquiry.

>> Pamela Karlan: Karlan is a well-known name in liberal legal circles. She's currently serving as the chair of the board of directors for the left-leaning American Constitution Society, and was the deputy assistant attorney general for voting rights at the Justice Department during the Obama administration.

Karlan has also argued before the U.S. Supreme Court several times, and is the co-founder of Stanford Law School's Supreme Court Litigation Clinic.

She is perhaps the least vocal about this current impeachment inquiry of all the witnesses on the panel, as it doesn't seem that Karlan has authored any columns outlining her stance on the inquiry or made any notable appearances about the proceedings so far.

Karlan was also a law clerk for Justice Harry Blackmun, and previously taught at the University of Virginia School of Law.

>> Noah Feldman: Feldman is a professor of constitutional law at Harvard and a columnist for BloombergViews, where he has weighed in on impeachment.

In a column last month, the professor warned House Democrats against "allowing too much legal talk to obfuscate the fundamental wrongness of Trump's conduct: using the might of his office to pressure a foreign country to destroy the candidate he thought most likely to threaten his re-election."

He specifically urged Democrats to stay away from "legalism" during the public proceedings, or feeling as if they have to prove that Trump has violated a specific legal statute as evidence he should be removed from office.

"The very definition of an abuse of power is for a sitting president to use his office for personal, partisan gain. Using the presidency to get Ukraine to investigate Biden was—obviously—a brazen attempt to gain unfair advantage in the 2020 election," Feldman wrote. "That abuse of power is a high crime and misdemeanor. It merits impeachment. And legalism shouldn't be allowed to distract the public from it."

Before joining Harvard, Feldman was a law clerk for U.S. Supreme Court Justice David Souter and later taught at the New York University Law School.

>> Michael Gerhardt: Wednesday's hearing won't be Gerhardt's first stint as a witness during an impeachment proceeding, as he played a similar role during the Clinton impeachment. He was the only bipartisan witness who testified at that hearing, and also talked impeachment with the House behind closed doors, according to his UNC biography.

Gerhardt is the author of two books on impeachment: "The Federal Impeachment Process: A Constitutional and Historical Analysis" and "Impeachment: What Everyone Needs to Know."

He has also been featured widely in media coverage about the current impeachment inquiry, weighing in on past proceedings and describing what a Senate trial could look like.

In an interview with Slate's Dahlia Lithwick last week, Gerhardt said that Trump has "dismissed the rule of law as being relevant to his life."

"Some of us who still take the Constitution rather seriously believe that those articles of impeachment that had been approved against Richard Nixon turn out to be relevant, as well, to the misconduct of President Trump," Gerhardt continued. "First, he has obstructed justice a variety of different ways. Second, he has asked the president of a foreign country—actually asked the presidents of a few different countries—to intervene in the next election on his behalf. And then third, he has refused to comply with more subpoenas than most people can count."

>> Jonathan Turley: Turley appears to be the Republican-called witness for this hearing. The GW Law School professor has previously defended the president on certain legal issues, including claims the Trump campaign colluded with Russia during the 2016 presidential race.

But Turley, like many Republicans, has publicly criticized how House Democrats have conducted their impeachment inquiry. In a column published by The Hill newspaper late last month, he described the ongoing proceedings as "an impeachment that seems designed to fail with an incomplete and conflicted record."

He pointed to Democrats failing to call prominent witnesses like former national security adviser John Bolton or acting White House Chief of Staff Mick Mulvaney in the impeachment inquiry.

"There may be an impeachable case to be made with Bolton, who teased about an undisclosed back story, but it will not be sustainable on this record," Turley wrote.

The law professor also made headlines in 2014, when he was hired as lead counsel in then-Speaker John Boehner's lawsuit against the Obama administration's Affordable Care Act.

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