In New York City, arguments have begun in a federal appeals case in which Haitian victims are seeking to hold the United Nations responsible for a cholera epidemic that killed more than 9,000 people. The U.N. peacekeepers are accused of negligently bringing cholera to the island during their deployment following the 2010 Haitian earthquake. But the United Nations is arguing it has immunity under a 1946 convention, and its lawyers did not attend Wednesday’s hearing.