Survivors and family members of nearly 700,000 people who have contracted cholera in Haiti are suing the United Nations for billions of dollars.
The lawsuit, which was filed in the US by the Institute for Justice and Democracy in Haiti, accuses the UN of covering up its role in starting the worst outbreak of the deadly disease in modern history.
Numerous scientific studies have linked the outbreak to UN peacekeeping troops who inadvertently carried the disease to Haiti from Nepal in October 2010.
It has now spread to Venezuela, Cuba and the Dominican Republic and killed more than 8,500 people.
Speaking on RTÉ’s Morning Ireland, Director of the institute Brian Concannon said it was proceeding with the court action in New York because the UN had blocked a resolution using its own internal procedures.
Mr Concannon said it is beyond any serious doubt that the UN is responsible.
"There's a host of studies and each serious study has come to the same conclusion that the Nepalese battalion was responsible," he said.
The UN maintains it has legal immunity from such compensation claims, but the Institute for Justice and Democracy in Haiti said the UN has not lived up to its obligations.
Human rights lawyers filed the suit in the US District Court in New York's Southern District, seeking $2.2 billion (€1.62bn) for the Haitian government to eradicate cholera along with unspecified damages for as many as 679,000 victims for personal injury, wrongful death, emotional distress, and loss of use of property and natural resources.
The lawsuit filed on behalf of Haitians and Haitian-Americans maintains that the cholera was introduced by UN troops brought to Haiti from Nepal, "a country in which cholera is endemic and where a surge in infections had just been reported."
"Haiti today has the worst cholera epidemic in the world," said Miami attorney Ira Kurzban, who announced the lawsuit at a joint news conference with the human rights groups Bureau des Advocats Internationaux (BAI) and Institute for Justice and Democracy in Haiti (IJDH).
"Before these events, Haiti did not know of cholera for 100 years. Cholera was brought to Haiti by UN troops," Mr Kurzban said.
The troops were stationed near a tributary of the Artibonite River and discharged raw sewage that carried a strain of cholera into Haiti, sparking the epidemic, the lawsuit said.
"The UN knew or should have know that its reckless sanitation and waste disposal practices posed a high risk of harm to the population, and that it consciously disregarded that risk, triggering an explosive epidemic," the civil rights groups said in a joint press release.
Asked to comment on the suit, UN spokesman Farhan Haq said: "We don't discuss claims brought against the UN".
UN human rights chief Navi Pillay said in Geneva yesterday that Haiti's cholera victims should be compensated, though she did not say who should compensate them.
An independent panel appointed by UN Secretary-General Ban Ki-moon to study the epidemic issued a 2011 report that did not determine conclusively how the cholera was introduced to Haiti.
But the US Centers for Disease Control and Prevention said evidence strongly suggested UN peacekeepers from Nepal were the source.