With Democrats taking control of the House this week, a key question facing the leadership is whether to pursue the impeachment of President Donald Trump. Morning Edition’s Joe Mathieu discussed how the federal impeachment process works, and what obstacles may stand in the way of a possible impeachment of the president with WGBH legal analyst and Northeastern law professor Daniel Medwed. The following transcript has been edited for clarity.

Joe Mathieu: So let's start with the basics as we always do. What does it actually take to initiate or trigger the impeachment process?

Daniel Medwed: It's essentially a two-step process. First, a majority of the House must vote for an indictment to impeach the president due to the commission of a high crime or misdemeanor. And second, the Senate holds a trial after which a supermajority — two thirds of the Senate body — must vote to convict and remove the president from office. Now, given the lack of clarity surrounding the definition of a high crime or misdemeanor, this process has always invariably been much more of a political process than a legal one.

Mathieu: So without a clear or firm definition of a high crime or misdemeanor, you think House Democrats could find President Trump has in fact committed one and begin the process?

Medwed: I think they could. Well, I don't think they should. And here's why. So on the one hand, yes the term is very nebulous. It's very subjective, which means that it's in the eye of the beholder — what constitutes a high crime or misdemeanor. This reminds me of Justice Potter Stewart's famous comment about obscenity. He knows it when he sees it. And I think likewise Congress, depending on the partisan lens, knows it when it sees a high crime and misdemeanor. After all, 20 years ago a majority of the House saw a high crime and misdemeanor in the conduct of Bill Clinton with respect to Monica Lewinsky and his comments regarding that incident. Nowadays, there are no shortage of potential hooks to hang your impeachment hat on, if you're a House Democrat who wants to go after Donald Trump.

But on the other hand, as a practical matter, when you look back at the history of impeachment proceedings — and I'm thinking specifically about the 15 or so cases involving lower court federal judges — the successful ones that resulted in impeachment seemed to have had a pre-existing criminal conviction before the impeachment process even started. So here we not only lack a criminal conviction for Donald Trump, but we also seem to lack the political will at least in the Senate to go after him. So if the House were to begin this process, I suspect it would die on the vine because the Senate wouldn't proceed apace. However, down the road, after the Mueller probe winds down, after a final report is issued maybe impeachment would be more likely.

Mathieu: Even without a criminal conviction like you say?

Medwed: I think that's right in part because I can't imagine a criminal conviction against Donald Trump happening anytime soon. Not only do the wheels of justice turn slowly, if an indictment came down today it would take a long time to resolve itself. There are also lingering arguments of varying degrees of merit about whether he warrants presidential immunity — that he can't be charged with a crime as long as he occupies the Oval Office. Also there are questions about his constitutional authority to pardon himself.

Mathieu: So let's get to that because a lot of people bring this up. Do you think he has the legal ability as the president to pardon himself?

Medwed: I'm a little reluctant to wade into these murky waters. There are arguments on both sides. I guess I dipped my toe into it by mentioning the "P" word. Maybe it's wishful thinking, but I do think the greater authority suggests that he can't pardon himself. But it's a real debate. Regardless, wherever you stand on the debate, when you look at the history of the Constitution and all of that, it does seem at a minimum he could do the good old Ford-Nixon tango and resign before the end of his term and have Pence pardon him. But the real issue here, I think the one that I want to underscore, is that even if he's pardoned by himself or by Pence, that wouldn't inoculate him from state criminal liability. He still could face the music for state crimes. And right now I hear Frank Sinatra's "New York New York" ringing in my brain because I think that the New York state attorney general, the county district attorneys in Manhattan and elsewhere, could possibly muster a case against him, and that ultimately he could face criminal charges.

Mathieu: We're gonna find out together with WGBH legal analyst and Northeastern law professor Daniel Medwed.