Four years ago this month a battalion of United Nations soldiers, fresh from a cholera outbreak in Nepal, allowed their sewage to flow into Haiti’s biggest river and, scientists say, sparked the deadliest acute epidemic of the century. An estimated 9,000 people have died—nearly double the death toll of the current Ebola outbreak—and an estimated 700,000 people have been infected. On Thursday, embattled victims finally got a day in court. What was most remarkable about the hearing in the U.S. District Court in Manhattan was not the lawyers’ arguments or Judge J. Paul Oetken’s pointed questions, but who was doing the arguing. The opposition to the thousands of Haitian cholera victims did not come from the U.N., which did not send a representative, but the United States government.

When cholera erupted in October 2010, responders and most of the international media assumed it was another in Haiti’s cycle of tragedies, a result of the magnitude-7.0 earthquake nine months before. That was way off. There had never been a documented case of cholera in Haiti before. The epidemic began, spread, and ultimately proved worst outside the quake zone. I was the resident Associated Press correspondent at the time. When I and, separately, University de la Mediterranée epidemiologist Renaud Piarroux unearthed evidence of the U.N. troops' likely role in sparking the outbreak, a cover-up was already underway. The World Health Organization and U.S. Centers for Disease Control and Prevention defied their own best practices and refused to investigate the epidemic’s source. Scientific evidence mounted anyway, but the U.N. leadership simply refused to acknowledge it.

In 2011, lawyers filed a class action suit on behalf of several thousand cholera survivors and victims’ families. They took the case first to the U.N. itself, only to be stonewalled for 15 months, then have the claims sent back stamped “not receivable.” Last year, the case went to U.S. federal court. The plaintiffs asked for a jury trial in which they will seek damages for the injuries and deaths, as well as fulfillment of a $2.2 billion plan to build the water, sanitation, and health infrastructure necessary to eradicate cholera from the island nation. There is reason to think that wouldn’t happen without legal force: In four years of the epidemic, the U.N. has raised just 10 percent of needed funds from member states.

The Obama administration is one major reason there hasn’t been a trial so far. The Justice Department has twice filed statements of interest with the court, arguing that the case should be dismissed on grounds that the U.N. enjoys “absolute immunity” from suit under its treaties and charter. Whether that immunity should be absolute, or whether the UN’s failure to offer victims an opportunity to seek redress should void it, is the question Thursday’s hearing was supposed to address. (As expected, Oetken did not announce a decision, which could take weeks.)

U.S. officials won’t say much about why they are dead set against letting those injured by the U.N.’s apparent negligence, some of whom were U.S. citizens and others who had extensive family in the Haitian diaspora here, so much as bring their case to court. The U.S. permanent mission to the U.N.—Samantha Power’s office—has repeatedly declined to comment on the matter. The State Department has said it is compelled to support U.N. immunity under its treaty obligations, but won’t go into further details. There were clues about the reasoning behind the position at the end of Thursday’s proceedings, however. Assistant U.S. Attorney Ellen Blain told the judge that allowing the suit to move forward “would create and open up a huge set of claims ... [from] private parties around the world." She said this would not only affect the U.N. but U.S. troops and personnel stationed overseas.

That echoed a fear recently expressed to me by a senior official knowledgeable about the case, who said that punching a hole in U.N. immunity and allowing a multibillion-dollar settlement could mean “not only the end of the peacekeeping but it could be the end of the U.N. altogether." (The official added that “some of the biggest donors to the U.N.” had been “absolutely clear on the point.”)

The cholera victims and their advocates argued in response that the U.N. cannot hope to be effective in promoting peace and the rule of law if it fails to live up to its own obligations. In court, Bea Lindstrom of the Institute for Justice and Democracy in Haiti argued for the plaintiffs that a failure to comply with Section 29 of the Convention on the Privileges and Immunities of the United Nations, which says the U.N. “shall make provisions for appropriate modes of settlement of” disputes, including those to which officials enjoy immunity, proved a “material breach” of that agreement—in other words, rendering the U.N.’s agreements, and the immunity they confer, void.

The advocates also tried to convince the judge that merely allowing the case to move forward to trial would fulfill a principle of justice. “The Haitian people are all too familiar with courts expressing sympathy with their plight, but closing their doors on them,” said Muneer Ahmad, a law professor at Yale University, who presented one of three amicus curiae briefs on behalf of the plaintiffs.

As a major funder of the U.N., the U.S. also has a monetary interest in the outcome of the case. The U.S. provides about a quarter of the annual peacekeeping budget. If the U.N. is forced to pay restitution for the catastrophe in Haiti, there is a good chance Americans could be left to pay part of the bill, as the erstwhile U.N. critics at the conservative Heritage Foundation have argued.

Judge Oetken, an Obama appointee confirmed in 2011, gave few indications where he might be leaning. He seemed interested in exploring Lindstrom’s argument that the UN’s failure to hold up its end of the bargain in Section 29 constituted a breach of contract and should void its immunity privilege. During the U.S. attorney’s presentation, Oetken presented Blain with a hypothetical in which she agreed in a contract to sell him a cow, and in a separate but implicitly related clause he agreed to pay her $100. Would he still be required to pay her the $100 if she failed to deliver the cow, the judge asked? Blain declined to play along. She responded only that treaties should be read “liberally” by courts, giving deference to the signatory government’s interpretation. “Even if the UN has completely breached [the convention] … that breach is irrelevant,” she argued.

At the same time, Oetken made clear he was taking seriously a number of precedents that could end the cholera victims’ case before it begins. Particularly daunting for the plaintiffs is Brzak v. United Nations, a 2010 case in which the U.S. Second Circuit Court of Appeals—Oetken’s superior court, to whom any trial ruling would likely be appealed—ruled that former employees of the U.N. High Commission for Refugees could not sue their employers over sex discrimination because of the U.N.’s immunity from suit.

The other thing blocking a trial has been the ability of U.N. officials to literally dodge the court’s process servers. U.N. Secretary-General Ban Ki-moon, a named defendant in the suit, has refused to receive court papers. Servers have mailed and faxed papers to the U.N. One tried tacking a summons to the door of his private residence in Manhattan. Another, representing a separate group of Haitian cholera victims suing in federal court in Brooklyn, tried to shove papers into his hand while he was walking to an Upper East Side speech.

In private conversations with U.N. officials, there seems to be a grudging acceptance—and even more pervasive sense of shame—that the peacekeepers were responsible for the massive epidemic, which not only caused tremendous loss of life but set back the Haitian economy and civil society that so many at the U.N. have pledged to help build. (Cholera’s corrosive power on Haiti’s medical infrastructure and society has been echoed in reports from the Ebola epidemic in West Africa. In a coincidence, the first person diagnosed with Ebola in New York City was admitted to nearby Bellevue Hospital Center hours after the hearing.) Ban traveled to Haiti this summer for the first time since the outbreak, where he affirmed a “moral responsibility” to end the cholera epidemic. As the U.S. takes the lead fighting the case in the courts, time will tell if the U.N. leader has the power or will to accept actual responsibility as well.

This post has been updated to reflect the official court transcript.