It is the world’s most important organization, yet remains one of the most dysfunctional.

This week a former United Nations employee described a pervasive culture of impunity inside the organization – one in which whistle-blowers are punished for exposing wrongdoing. James Wasserstrom, a veteran American diplomat, said he was fired from his job and detained by U.N. police – who searched his apartment and placed his picture on wanted posters – after he reported possible corruption among senior U.N. officials in Kosovo.

“It’s supposed to be maintaining the ideals of human rights, the rule of law and anti-corruption,” Wasserstrom said in an interview. “And it doesn’t adhere to them on the inside.”

The United Nations is under attack as well for its decision last month to pay no compensation to the families of 8,000 Haitians who died and  646,000 who fell ill from a 2010 cholera outbreak that experts believe Nepalese U.N. peacekeepers set off in the country.

The organization, though, remains a vital tool. On Thursday, President Barack Obama used a White House meeting with U.N. Secretary General Ban Ki-moon to pressure North Korea. Administration officials hope that punishing new U.N. economic sanctions, supported by China for the first time, will cause North Korea to end its saber rattling.