Each special city had a population of at least 200,000, and was delegated functions[specify] normally carried out by prefectural governments.
The category of special cities was established by the Local Autonomy Law, article 252 clause 26.
They were designated by the Cabinet after a request by a city council and a prefectural assembly.
Special cities that have not been promoted may still retain autonomy, and are called special cities for the enforcement period (施行時特例市, Shikōji Tokurei shi), but this is regarded as a temporary arrangement.
They were also different from the special (designated) cities (特別市, tokubetsu-shi) that were legally established under the Local Autonomy Law between 1947 and 1956, in an arrangement that was never implemented.