Evidencial value of documents

Respected Sir

As per your query the correct law which would be applicable in this case would be the registration act. It is a very simple answer.There is a list of documents which are mentioned in the registration act section 49 where in the list includes all the documents to have compulsary registration to have any legal binding upon them.Without the registration they are of no use either as evidence or to serve the purpose of their contents. If the documents you are talking about falls in the list given in tht section then yes they need to be compulsarily registered to be used as evidence. If not there is no mandate.

As far as your query with regard to the reason why these documents are prepared on stamp paper is because they are those documents in which you are in one way or the other seeking assistance from the govt to aid you in attaining the purpose of the document. Hence you have to purchase an appropirate amount of stamp paper and use it as legitimate proof of the fact that you have done the registration after paying the fee to the govt.  It is analogous to paying court fee :)

Hope i helped