Overview
A witness's statement on oath is the totality of that witness's written evidence, and both the facts deposed and any attached documents draw their evidential force from it. Where a statement is incompetent or absent, the witness's testimony and any annexed documents cannot sustain the case - a rule meant to ensure fairness in trial preparation and prevent surprise. The oath requirement also serves a deeper purpose: swearing statements before a designated oath officer impresses upon the deponent the solemnity of testimony, discourages falsehood, and assures authenticity, especially as written depositions increasingly replace oral evidence-in-chief.
Under the Oaths Act 2004 and the Evidence Act 2011, statements must be sworn before a competent authority, not before parties or their counsel; non-compliance may render a statement incompetent and even go to the root of the evidence. In practice, counsel often attack opposing cases by extracting admissions in cross-examination that a witness swore the statement in a lawyer's office, at home, or elsewhere without an oath officer present. Judicial responses have been inconsistent, with courts divided between strict compliance and a more liberal emphasis on presumptions of regularity and absence of prejudice - making the Supreme Court's decision in Katagum v. Umar & Anor particularly instructive.
