The United Nations (commonly abbreviated to UN) is a conglomerate of nations based on Earth. It has a special Justice League charter, giving the League jurisdiction in the signatories' territory,as well as granting the League UN funding.
Lobo attacked the United Nations building in New York. He was trying to get to the impostor Tseng. Batgirl and Wonder Girl tried to stop Lobo, but he achieved his goal. He exposed Tseng as a Krolotean in a robot suit. He left the building with the Krolotean.
After Captain Atom presented evidence that the Reach were hostile invaders during an emergency session of the UN, and following a unanimous vote, Secretary Tseng rescinded the Reach's invitation to stay on Earth, and demanded they leave.
Following public outcry (lead by G. Gordon Godfrey) over his initial support of the Reach, Tseng Dangun resigned as UN Secretary-General.
Lex Luthor became the new UN Secretary-General. He placed significant restrictions on Justice League activity, including requiring the unanimous approval of the Security Council before beginning humanitarian missions.
In January, the Joker staged an attack on the UN General Assembly with Joker venom bombs. The Bat-family defused the bombs and apprehended Joker.
The UN held a Meta-human summit, where Catherine Cobert announced the resignations of numerous members of the Justice League in protest of UN restrictions. The ambassadors had a heated debate on the activity of meta-humans, heroes and vigilantes.
Secretary-General Luthor addressed the General Assembly regarding the Justice League's rescue of numerous meta-humans from a meta-trafficking chain involving Goode World Studios. He criticized the League for failing to work with local authorities.
As protestors (including a disguised Chameleon Boy) gathered outside UN headquarters, inside Luthor decried the allegations against him as "fake news". He was interrupted by Superboy, who announced he was a Genomorph clone of Superman and Lex Luthor, created by Luthor and Cadmus. Ambassador Garth called for an immediate vote of no confidence in Luthor.
On or shortly after September 9, a dedication ceremony was held by Black Lightning and Troia for the building of a new Hall of Justice to begin the following Spring on Justice Island, opposite United Nations headquarters. Troia wanted it to represent a new era of partnership between the two organizations.