According to Code of Criminal Procedure, 1973, the State may declare by notification that a City or a Town where population exceeds 10 lakh [1.0 million] and that area shall be called a Metropolitan Area under this Code. While from the date of commencement of the Code, Bombay, Madras, Calcutta and Ahmedabad were declared as Metropolitan Area.

The State Government by notification extend or reduce the limit of the Metropolitan Area but it shall not reduce the population of area less than 10 lakh.

Even, otherwise, population of the Metro Area has gone below 10 lakh, even the State Government by notification ceased to have called it a Metro from such date, howsoever, the trial, inquiry or appeal powers of the Courts shall not be ceased.

Even if the State does any alteration of the extent of the Metro area, the powers of the Criminal Courts can never be reduced.