law: The Legal Metrology Act, 2009
  12. Any custom,
  
  usage, etc., contrary to standard weight, measure or numeration to be void. -
  Any custom, usage,
  
  practice or method of whatever nature which permits a person to demand, receive
  
  or cause to be demanded or received, any quantity of article, thing or service
  
  in excess of or less than, the quantity specified by weight, measure or number
  
  in the contract or other agreement in relation to the said article, thing or
  
  service, shall be void.