Article 1, Section 9, Clause 8 of The Constitution, the so-called “Emoluments Clause,” states clearly that:

No Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince or foreign State.

As this article in Business Insider explains:

One of dozens of proscriptions in the Constitution aimed at fighting corruption, the emoluments clause is one of the only ones that actually applies to the president. Critics of President-elect Donald Trump‘s potential financial conflicts of interest are pointing to it amid reports about his extensive business dealings with foreign entities, including the state-owned Bank of China.

Some critics point to recent troubling reports — that Trump allegedly asked British politician Nigel Farage to push against wind farm development near a Trump golf course, and that the president-elect reportedly lobbied Argentinian president Mauricio Macri to help expedite a stalled Buenos Ares development — as signs that Trump is already using his clout improperly.

In a meeting Tuesday with the New York Times, Trump seemed to confirm the reports about his talk with Farage.

But Trump’s camp is denying the reports about Macri, and the president-elect tweeted on Monday night that his “interests in properties all over the world” have been public knowledge for awhile and that it’s “only the crooked media” that is making “this a big deal” now.