The General Assembly is the governing body that unites all the species of New York City in accordance with the New York Integration Treaty. The treaty is enforced by the Department of Integration. The General Assembly is headed by the DOI director, and it includes representatives from each species in the treaty.
In the episode "The Roast of Twayne the Boneraper", Mark Lilly shuts down the Department of Birthdays when he becomes the DOI's director. This leads to the various species seceding from the General Assembly, thus, the dissolution of the New York Integration Treaty and a city wide riot. The assembly is restored when Twayne Boneraper resumes his seat in the DOI.