As the host of the United Nations, the U.S. is supposed to let everyone come to the annual U.N. General Assembly, not just the people it likes.
But this year, the proposition is being put to the test. Sudan's president, Omar al-Bashir, was indicted three years ago by the International Criminal Court on genocide charges stemming from the mass killings in Sudan's western Darfur region.
Bashir has also applied for a visa to the U.N. meetings next week.
"Such a trip would be deplorable, cynical and hugely inappropriate," says Samantha Power, the U.S. ambassador to the U.N.
The State Department hasn't yet made a decision, and officials say they are considering many factors, including the outstanding warrant against him.
These are new legal waters, says Northwestern University's David Scheffer, a former U.S. ambassador at large for war crimes issues, who helped negotiate the treaty that set up the ICC.
"What some people might regard as odious characters certainly [have] appeared on the podium," says Scheffer. "But we have not had an indicted war criminal do so. That changes the game."
World leaders are entitled to diplomatic immunities while at the U.N., but Scheffer says there are conflicting laws and treaty obligations to work through.
He thinks there are ways for U.N. Secretary General Ban Ki-moon to deny Bashir access or for the U.S. to arrest him.
One option is a U.N. Security Council resolution that requires Sudan to cooperate with the International Criminal Court.
"The mere fact that President al-Bashir is seeking to travel to New York, with or without a visa, is an act of non-cooperation with the ICC because the only plane he should be getting on is one to the Hague," says Scheffer.
The U.N. secretary general is urging Bashir to surrender to the ICC in the Hague. But if he does show up in New York, U.N. member states and employees are being told to limit their contacts with him.
Briggite Suhr, who is with the Coalition for the International Criminal Court, an advocacy group, says that could be embarrassing for the Sudanese leader.
"Other heads of state would avoid meeting with him. Other heads of state or high U.N. officials would avoid being seen shaking his hand, would avoid standing next to him on a podium," she says. "Perhaps if he were to speak to the U.N., he would be speaking to a largely empty room."
Scheffer says the U.S. and U.N. should make all of this clear to Bashir to dissuade him from coming, rather than, as some suggest, lure him to New York to arrest him.
"That would be a very, shall we say, devious strategy on the part of both the U.S. and U.N. and might backfire poltically, particularly in Africa, if they were to do that," he says.
The ICC is already facing a lot of criticism from African countries who feel they are unfairly singled out. Kenya, for one, is threatening to pull out. Its new president, Uhuru Kenyatta, is accused by the court of orchestrating the deadly violence after the 2007 election, an allegation he denies.
Suhr, of the coalition for the ICC, says the Kenyan issue and, in a different way, Sudan, puts the ICC in an awkward spot.
"It's one of those uncomfortable realities of how [the ICC] is situated in the world. It doesn't control what happens at the U.N. in that way. It doesn't have its own police force," she says. "It understands the existence of diplomatic immunity at the U.N. and it understands that it kind of sits at that crossroads."
She's encouraging the U.S. and the U.N. to look into legal alternatives. Perhaps, she says, a country could arrest him in transit on his way to or from the U.N.