Section 138: Burden of proving fact necessary to be proved to make evidence admissible.

1 The burden of proving any fact necessary to be proved in order to-
a enable a person to adduce evidence of some other fact; or
b prevent the opposite party from adducing evidence of some other fact, lies on the person who wishes to adduce, or to prevent the adduction of such evidence, respectively.

2 The existence or non-existence of facts relating to the admissibility of evidence under this section is to be determined by the court.