law: Code of Criminal Procedure Act, 1973
  
  8.Metropolitan areas.-
  (1) The State Government may, by notification,
  
  declare that , as from such date as may be specified in the notification, any
  
  area in the State comprising a city or town whose population exceeds one
  
  million shall be a metropolitan area for the purposes of this Code.
  (2) As from the commencement of this Code, each of the Presidency-towns of 
  
   Bombay ,  Calcutta and  Madras and the city of 
  
   Ahmedabad shall be deemed to be
  
  declared under sub-section (1) to be a metropolitan area.
  (3) The State Government may, by notification, extend, reduce or alter the
  
  limits of a metropolitan area but the reduction or alteration shall not be so
  
  made as to reduce the population of such area to less than one million.
  (4) Where, after an area has been declared, or deemed to have been declared to
  
  be, a metropolitan area, the population of such area falls below one million,
  
  such area shall, on and from such date as the State Government may, by
  
  notification, specify in this behalf, cease to be a metropolitan area; but
  
  notwithstanding such cesser, any inquiry, trial or appeal pending immediately
  
  before such cesser before any Court or Magistrate in such area shall continue
  
  to be dealt with under this Code, as if such cesser had not taken place.
  (5) Where the State Government reduces or alters, under sub-section (3), the
  
  limits of any metropolitan area, such reduction or alteration shall not affect
  
  any inquiry, trial or appeal pending immediately before such reduction or alteration
  
  before any Court or Magistrate, and every such inquiry, trial or appeal shall
  
  continue to be dealt with under this Code as if such reduction or alteration
  
  had not taken place.
  
  Explanation.-In this section, the expression "population"
  
  means the population as ascertained at the last preceding census of which the
  
  relevant figures have been published.