The position is that a tainted witness is either an accomplice or a witness who has an interest to defend or a purpose to serve in a case in which he is called upon to give evidence as a witness. It has to be shown that the witness has some peculiar interest to protect or purpose to serve in the evidence he gives in a case in order to make him a tainted witness.
– M.L. Garba JCA. Odogwu v. Vivian (2009) – CA/PH/345/05