law: The Central Goods and Services Tax Act, 2017
  144. Presumption as to documents in certain cases.-
  Where any document-
  (i) is produced by any person under this Act or any other law for the time being in force; or
  (ii) has been seized from the custody or control of any person under this Act or any other law for the time being in force; or
  (iii) has been received from any place outside India in the course of any proceedings under this Act or any other law for the time being in force, and such document is tendered by the prosecution in evidence against him or any other person who is tried jointly with him, the court shall-
  (a) unless the contrary is proved by such person, presume-
  (i) the truth of the contents of such document;
  (ii) that the signature and every other part of such document which purports to be in the handwriting of any particular person or which the court may reasonably assume to have been signed by, or to be in the handwriting of, any particular person, is in that person's handwriting, and in the case of a document executed or attested, that it was executed or attested by the person by whom it purports to have been so executed or attested;
  (b) admit the document in evidence notwithstanding that it is not duly stamped, if such document is otherwise admissible in evidence.