law: Narcotic Drugs and Psychotropic Substances Act, 1985
  31. Enhanced punishment for certain
  
  offences after previous conviction.
  (1) If any person who has been convicted of the commission of,
  
  or attempt to commit, or abetment of, or criminal conspiracy to commit, any of
  
  the offences punishable under section 15 to section 25 (both inclusive) is
  
  subsequently convicted of the commission of, or attempt to commit, or abetment
  
  of, or criminal conspiracy to commit, an offence punishable under-
  (a) section 15 to section 19, clause (ii) of
  
  section 20 and section 21 to section 25 (both inclusive), he shall be punished
  
  for the second and every subsequent offence with rigorous imprisonment for a
  
  term which shall not be less than fifteen years but which may extend to thirty
  
  years and shall also be liable to fine which shall not be less than one lakh
  
  fifty thousand rupees but which may extend to three lakh rupees;
  (b) clause (i) of section 20, he shall be
  
  punished for the second and every subsequent offence for a term which may
  
  extend to ten years and shall also be liable to fine which may extend to one
  
  lakh rupees:
  Provided that the court may, for reasons to be recorded
  
  in the judgment, impose,-
  (i) in a case falling under clause (a), a fine exceeding three
  
  lakh rupees; and
  (ii) in a case falling under clause (b), a fine exceeding one
  
  lakh rupees.
  (2) Where any person is convicted by a competent court of
  
  criminal jurisdiction outside India under any law corresponding to the
  
  provisions of section 15 to section 25 (both inclusive), section 28 and section
  
  29, such person, in respect of such conviction, shall be dealt with for the
  
  purposes of sub-section (1) as if he had been convicted by a court in India.