"Duly constituted legislative body" refers to a group of lawmaking officials who have been established in accordance with the relevant laws and regulations. Some synonyms for this phrase include properly formed legislative body, lawfully created legislative assembly, legally established parliament, authorized lawmaking body, and validly constituted council. All of these phrases essentially refer to the same thing, which is a group of lawmakers who have the authority and legitimacy to enact laws that are binding on their constituents. It is important for the public to have confidence in the authority and legality of their government institutions, and using precise and accurate language to describe them is one way to foster this trust.