Section 4 in The Code of Criminal Procedure 1973
Title: Trial of offences under the Indian Penal Code and other laws
(1) All offences under the Indian Penal Code (45 of 1860) shall be investigated, inquired into, tried, and otherwise dealt with according to the provisions hereinafter contained.
(2) All offences under any other law shall be investigated, inquired into, tried, and otherwise dealt with according to the same provisions, but subject to any enactment for the time being in force regulating the manner of place of investigating, inquiring into, trying or otherwise dealing with such offences.
Nothing contained in this Code shall, in the absence of a specific provision to the contrary, affect any special or local law for the time being in force, or any special jurisdiction or power conferred, or any special form of procedure prescribed, by any other law for the time being in force.
Title: Classes of Criminal Courts
Besides the High Courts and the Courts constituted under any law, other than this Code, there shall be, in every State, the following classes of Criminal Courts, namely:--
(i) Courts of Session;
(ii) Judicial Magistrates of the first class and, in any metropolitan area, Metropolitan Magistrates;
(iii) Judicial Magistrates of the second class; and
(iv) Executive Magistrates
Title: Territorial divisions
(1) Every State shall be a sessions division or shall consist of sessions divisions; and every sessions divisions shall, for the purposes of this Code, be a district or consist of districts:
Provided that every metropolitan area shall, for the said purposes, be a separate sessions division and district.
(2) The State Government may, after consultation with the High Court, alter the limits or the number of such divisions and districts.
(3) The State Government may, after consultation with the High Court, divide any district into subdivisions and may alter the limits or the number of such sub-divisions.
(4) The sessions divisions, districts and sub-divisions existing in a State at the commencement of this Code, shall be deemed to have been formed under this section.
Title: 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.