THE signature cocktail at the bar of the Trump International Hotel, in the Old Post Office building in Washington, is a $100 vodka potion served with oysters and caviar. It is called “The Benjamin” after Benjamin Franklin, America’s first postmaster-general. “You can see anyone from Rudy Giuliani to foreign dignitaries to businessmen from Dubai here,” says a bartender, who serves drinks under a vast American flag on loan from the Heritage Foundation, a conservative think-tank. She likes her job for the “exposure” it affords. Franklin, a signatory to the constitution, may not have been so impressed.

Over the 230 years since then, no court has had occasion to weigh in on the meaning of two so-called “emoluments” clauses in America’s founding document. One says presidents may receive only their salary, and no other payment, from the federal government or the states. The other bans federal officials from receiving “any present, emolument, office, or title, of any kind whatever” from a foreign state without the approval of Congress.

Donald Trump handed control of the Trump Organisation to his sons and a trustee in January. President Trump’s lawyer said back then that he would turn “leadership and management” of his global business empire over to his sons, but he continues to be its primary owner, and the handover was anything but blind: with updates at least every quarter, Eric Trump keeps his father well apprised of how his businesses are faring.

Since the election, the governments of Bahrain and Kuwait have both held events at the Washington hotel, cancelling their reservations at other venues. The embassy of Azerbaijan partied in its “Lincoln Library”. Saudi Arabia went on a $270,000 splurge, lobbying against legislation that allows Americans to sue foreign governments over terror attacks. After a visit in April Kaha Imnadze, Georgia’s ambassador to the UN, tweeted: “Great hotel and so far the best service I’ve seen in the United States! Keep it up!” Mr Trump promised to donate all hotel profits from foreign governments to the Treasury. Last month the Trump Organisation put out a strange brochure clarifying that it would not require foreign guests to identify themselves, as that would “diminish the guest experience of our brand”.

The hotel is just the tip of the iceberg, says Richard Painter, a law professor at the University of Minnesota who served as George W. Bush’s ethics lawyer. According to a financial disclosure report, the president owns or controls 500 businesses in two dozen countries. Some have already become politically entangled. Take Mr Trump’s deal in Turkey. Incensed by Mr Trump’s comments last year, the president, Recep Tayyip Erdogan, threatened to strip his name from Trump Towers Istanbul, a licensing deal worth several million dollars. After Mr Erdogan backpedalled, Mr Trump lavished him with praise and welcomed him to the White House. The Philippines’ president, Rodrigo Duterte, made the head of the company that built Trump Tower Manila a special trade envoy to America.

Mr Trump, a fan of seeing people in court, now faces four different lawsuits over his conflicts of interest. One filed by the Democratic attorneys-general of Maryland and the District of Columbia, accuses the president of violating both anti-corruption rules. Another, filed by nearly 200 Democratic Congressmen, argues that the president has failed to seek Congress’s permission before accepting foreign gifts, as the Emoluments clause says he must.

The Department of Justice has already responded to a challenge from Citizens for Responsibility and Ethics in Washington (CREW), a watchdog group, by urging the court to dismiss charges. CREW does not have the right to sue, the administration argued, and courts have no authority to stop presidents carrying out their “official duties”. This back-of-the-hand response will be harder to support in the suit brought by the states, which features sovereign entities as plaintiffs and which, according to Joshua Matz, a lawyer, and Laurence Tribe, a professor of law at Harvard, has an “exceptionally powerful” justification for legal standing. Mr Matz and Mr Tribe, who helped design the lawsuit, point to cases where Republicans turned to state governments as plaintiffs to challenge Barack Obama’s agenda.

The challenge to Mr Trump’s business interests, which the administration dismissed as a merely partisan attack, will not be resolved in a flash. The administration has 60 days to file its first response. If the court then permits the case to move forward—not a certainty, given the novel constitutional claims at stake—the clash will turn to whether the plaintiffs may force Mr Trump to hand over tax returns as evidence of his business ties. That struggle alone could consume the judiciary for some time, perhaps eventually involving the nine justices of the Supreme Court.