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.