Earlier this week, a federal judge ruled that a lawsuit alleging that President Donald Trump is violating the emoluments clause in the Constitution – essentially profiting from his office via his Trump International Hotel in Washington – could move forward. Emoluments aren’t something the average person knows about, and most people aren’t following this story closely. But the lawsuit has the potential – emphasis on “potential” – to force Trump to divest himself totally of his various business interests or walk away from the White House. I reached out to Georgetown Law professor John Mikhail, who has done considerable scholarly work on emoluments, to explain why they matter and whether this ruling poses a real threat to Trump. Our conversation, conducted via email and lightly edited for context, is below. Cillizza: Define “emolument.” And explain why we are talking so much about this when it comes to Donald Trump’s White House. MIkhail: When the Constitution was written, “emolument” was a flexible term that generally meant “profit,” “gain, “advantage,” or “benefit.” It was commonly used in ordinary English to refer to advantages or benefits of different types. For example, government salaries, payments on a contract, the interest on a loan, and the profits from ordinary commercial transactions were all referred to as “emoluments.” So, too, was the rental income earned by churches, halls and boarding houses. People are talking so much about emoluments now because there is a clause in the Constitution that forbids federal officials from receiving emoluments – that is, profits, advantages or benefits – from foreign governments without the consent of Congress. Since the start of his presidency, Trump has been doing just that. As a result, several lawsuits have been brought against him in order to stop these constitutional violations. Cillizza: Trump promised he was removing himself from the day-to-day operations of his company. So why is this still an issue? Mikhail: Even though President Trump promised to remove himself from the day-to-day operations of his businesses, he refused to divest his ownership interests in those companies. As a result, he continues to earn profits, advantages, and benefits from commercial transactions with foreign governments. The Constitution forbids federal officials from doing this without the consent of Congress. It’s an important issue because the Constitution is the “supreme law of the land” and the foundation of our democracy. Cillizza: How big a deal was the court ruling earlier this week that allowed the emoluments case to proceed? What’s the big takeaway from the judge’s ruling? Mikhail: This week’s ruling was a very big deal because it was the first time a federal judge has decided on the constitutional meaning of “emolument.” Judge (Peter) Messitte wrote a thoughtful and well-researched opinion after carefully considering all of the relevant arguments presented to him by the President, the attorneys general of Maryland and the District of Columbia, and many independent experts. The main takeaway is that the judge denied President Trump’s motion to dismiss the case and held that the type of commercial profits he has been receiving from foreign governments are covered by the clause. Cillizza: What’s the worst-case scenario for Trump in the legal proceedings surrounding emoluments? Best-case? Mikhail: Ultimately, the worst-case scenario for President Trump is that this case will effectively force him to choose between continued ownership of his businesses and his presidency. This might happen if a federal court orders the President to divest his ownership interests in his companies or to stop doing business with foreign governments. The emoluments clause violations uncovered by this lawsuit also could conceivably enter into impeachment proceedings against him. By contrast, the best-case scenario for President Trump would be if Judge Messitte’s decision to let this case go forward gets overturned on appeal, and if the other lawsuits against him fail as well. In that case, several plaintiffs would have tried to bring a halt to the President’s alleged violations, but the President would have ultimately prevailed. Cillizza” Finish this sentence: “How this case gets resolved will have a __________ impact on future presidents and their businesses.” Now, explain. Mikhail: “Questionable.” President Trump is unique in the extent to which he has refused to play by the rules that have been applied to every other president. All other modern presidents have willingly complied with the constitutional norms, federal laws and established customs designed to prevent corruption, conflicts of interest and undue foreign influence. [Editor’s note: Trump is also unique in that he has a massive business empire with his name plastered all over it, complicating attempts to totally distance himself from it.] Furthermore, President Trump is unique in the extent to which he has flouted these norms, laws and customs. No other individual has ever entered office intending to maintain such a vast business empire while also serving as President. It seems reasonable to assume – or at least to hope – that the United States will not face this problem again, either because the federal courts will eventually enforce the Constitution or because no one will ever test its limits in this way again. On the other hand, a more pessimistic take would be that the genie is now out of the bottle. Particularly if President Trump manages to win these lawsuits, future presidents might also seek to profit off the presidency. In that case, the anti-corruption principles embedded in the Constitution will have been dramatically undermined – and the United States will be much worse off as a result.