why has constitution made untouchability a punishable offence?

(i) The constitution mentions an extreme form of social discrimination, the practice of untouchability and clearly directs the government to put an end to it.
(ii) The practice of untouchability has been forbidden in any form.
(iii) Untouchability here does not only mean refusal to touch people belonging to certain castes. It refers to any belief or social practice which looks down upon people on account of their birth with certain caste labels.
(iv) Such practice denies them interaction with others or access to public places as equal citizens. so, the constitution made untouchability a punishable offence.