The United Nations are a group of the most powerful nations who were first mentioned in Champion. Toward the end of Champion it is revealed that they had Anden and the Colonies Chancellor sign treaty papers thus ending the longtime feud between the two nations.
The United Nation's primary role is to maintain peace and unity between the nations of the world. Before the events of Legend, the United Nations contained 193 sovereign nations. The Security Council, a major organ of the entire organization, contained five nuclear powers that had permanent seats. Those countries were Russia, China, Great Britain, France, and the United States of America. Each country held the veto power, in which they could utilize it to block legislature that may go against their interests.
In the Legend timeline, the role of the United Nations seem to remain unchanged, but internally there seem to have been major changes in the structure. For example, Africa seems to dominate the organization as it is a major power in this timeline. Despite the fact that the United Nations is an influential organization, it is still lacking in its ability to solve disputes among nations. The book Prodigy shows that the United Nations is working to solve the strife between the Republic and the Colonies of America to no avail.