One of several legal questions swirling around Donald Trump's presidency concerns a provision of the Constitution known as the Emoluments Clause. Morning Edition Host Joe Mathieu discussed that provision, and its application to the president, with Northeastern Law Professor and WGBH News Legal Analyst Daniel Medwed. The transcript below has been edited for clarity.

Joe Mathieu: Let's start with the basics, as we always do. Tell us about the Emoluments Clause.

Daniel Medwed: Well, frankly, before Inauguration Day 2017, I would have been hard-pressed to give you an answer. But it's contained in Article 1, Section 9 of the Constitution, and it's designed to prevent federal officials from accepting “any present emolument office or title of any kind whatever from any king, prince or foreign state.” And it emerged out of a concern in the 18th century about wealthy Europeans plying American ambassadors with lavish gifts to curry favor and influence foreign policy. Apparently, get this, Benjamin Franklin received a diamond-encrusted snuff box from the King of France. And this caused a lot of consternation among the framers — this idea that our government could be bought with foreign riches.

Mathieu: To receive a present or a title from a foreign state or a king, as you said, a prince, whomever it is, is something we can get our heads around. But have courts interpreted this term, emolument, differently?

Medwed: Well as far as I can tell, there has never been a major court case, let alone a Supreme Court decision, interpreting this clause. The plain meaning of the term derives from latin, and it refers to profit gain or advantage, essentially. Now, we might have more clarity on the legal front about its definition, because there's not just one emoluments clause case pending against Trump, but three separate ones pending in federal court, including one in Maryland that's entered the discovery phase and is on the precipice of going to trial.

Mathieu: So let's talk about that one. What's the basis for the litigation in Maryland?

Medwed: It's a fascinating case. The attorneys general of the District of Columbia and Maryland have targeted revenue from one of Trump's signature properties, his Trump International Hotel in the Old Post Office Building right near the White House. And the theory behind the plaintiff's suit is that the Emoluments Clause not only bans direct benefits, say the snuff box or an envelope full of cash, but also indirect benefits, like the income accrued through foreign nationals purchasing large batches of hotel rooms and event space in that facility.

Now it appears as though the federal judge in Greenbelt, Maryland, who is overseeing this case, shares this broad interpretation of the clause, because he's allowing the case to go forward and he's ordered discovery. In the last week or two, in fact, the plaintiffs have issued, I believe, 37 subpoenas including to 13 Trump-backed business entities and to the General Services Administration, which is the federal agency that leased back that post office building to the Trump Organization. Now unsurprisingly, Trump is digging in his heels and fighting back.

Mathieu: What argument is he making?

Medwed: Well, there are a whole bunch of them that he's made throughout the litigation. And in fact on Friday, if I recall, his lawyers tried to ask the 4th Circuit Court of Appeals to intervene and stop the discovery.

But here are some of the big arguments. First, and pretty obviously, he's arguing that the emoluments clause should be interpreted narrowly, to just bar direct benefits. Second, he's claiming presidential immunity, which is a patently absurd argument in this context, because after all, this clause is targeted at federal officials who take gifts. They're clearly not immune. And lastly, even if he's not immune, so his lawyers say, then as a matter of practical concerns, he shouldn't be sued because it will distract him from this heavy burden of governing the country. Again, a patently absurd argument, because he seems to take to Twitter every other day to threaten people with private lawsuits. He doesn't seem to be distracted when he's the initiator of litigation. Look at the list of people he's threatened: Author Michael Wolf, ex-CIA chief John Brennan, he's mired in litigation with the actress porn star Stormy Daniels. So I think those arguments are pretty specious. And this case will probably go to trial.