law: Drugs and Cosmetics Act, 1940
  19. Pleas
  (1) Save as hereinafter provided in this section, it shall be no
  
  defense in a prosecution under this Chapter to prove merely that the accused
  
  was ignorant of the nature, substance or quality of the drug 87[or
  
  cosmetic] in respect of which the offence has been committed or of the
  
  circumstances of its manufacture or import, or that a purchaser, having bought
  
  only for the purpose of test or analysis, has not been prejudiced by the sale.
  (2) 88[For the purposes of section 18 a drug shall
  
  not be deemed to be misbranded or 89[adulterated or spurious] or to
  
  be below standard quality nor shall a cosmetic be deemed to be misbranded or to
  
  be below standard quality] only by reason of the fact that-
  (a) there has been added thereto some
  
  innocuous substance or ingredient because the same is required for the
  
  manufacture or preparation of the drug 87[or cosmetic] as an article
  
  of commerce in a state fit for carriage or consumption, and not to increase the
  
  bulk, weight or measure of the drug 87[or cosmetic] or to conceal
  
  its inferior quality or other defects; or
   90  [***]
  (b) in the process of manufacture, preparation
  
  or conveyance some extraneous substance has unavoidably become intermixed with
  
  it: provided that this clause shall not apply in relation to any sale or
  
  distribution of the drug 87[or cosmetic] occurring after the vendor
  
  or distributor became aware of such intermixture.
   91  [(3) A person, not being the manufacturer of a drug or
  
  cosmetic or his agent for the distribution thereof, shall not be liable for a
  
  contravention of section 18 if he proves-
  (a) that he acquired the drug or cosmetic from
  
  a duly licensed manufacturer, distributor or dealer thereof;
  (b) that he did not know and could not, with
  
  reasonable diligence, have ascertained that the drug or cosmetic in any way
  
  contravened the provisions of that section; and
  (c) that the drug or cosmetic, while in his
  
  possession was properly stored and remained in the same state as when he
  
  acquired it.]