Onubogu and Anor v. The State (1974) 9 S.C. 1, 20: the Supreme Court opined that where in a criminal case, one witness called by the prosecution’ contradicts another prosecution witness on a material point, the prosecution ought to lay some foundation, such as showing that a witness was hostile, before they can ask the court to reject the testimony of one witness in preference for the evidence of the discredited witness. It is not competent for the prosecution to discredit one and accredit the other.
WHO IS A TAINTED WITNESS?
However, and for whatever it is worth, the law is settled that a tainted witness is a person who is either an accomplice or who on the evidence may be regarded as having some purpose of his/her own to serve – see R vs Enahoro (1964) NMLR 65; Ifejirika vs The State (1999) 3 NWLR (pt. 593) 59; Ogunlana vs The State (1995) 5 NWLR (Pt. 395) 266.
— W.S.N. Onnoghen, JSC. Moses v State [2006] – S.C.308/2002