ABSTRACT
Sections 53-57 of the Youth Justice and Criminal Evidence Act 1999 constitute a code governing the competence and capacity to be sworn of all persons tendered as witnesses in criminal cases. Where a potential witness has a defective intellect, therefore, the tests to be applied and the procedure for determining them are the same as have already been described in relation to children. It follows that a person with defective intellect may be able to give evidence in criminal, but not in civil, proceedings. In criminal proceedings, provided he satisfies the basic test for competence, he will be able to give evidence – if not sworn, then unsworn. In civil proceedings, an adult witness with defective intellect must be able to satisfy the Hayes test and be sworn; if he cannot do so, there is no provision enabling him to give unsworn evidence.
