Set to be introduced in January by Ms Warren and a group of
Democratic senators, the bill will invoke the little-known Emoluments
Clause of the constitution, which forbids the President from accepting
gifts or favours from foreign actors.

Under Article I, Section 9 of the constitution, the President is
forbidden from “accept[ing] any present, emolument, office, or title, of
any kind whatever, from any king, prince, or foreign state.”

The senator said that “experts have concluded that ‘[c]orporations
owned or controlled by a foreign government are presumptively foreign
states under the Emoluments Clause.’

(via Donald Trump faces impeachment if new conflicts of interest bill passed | The Independent)