A s 165 warning must address the witness's mental state at the time of giving evidence, not only at the time of the events in question. Where a witness has given an undertaking to give evidence as part of a sentencing process, the jury must be warned that the witness's sentence could be increased for non-compliance, as this provides a motive to lie. A Crown Prosecutor must not invite the jury to rely on a sentencing judge's assessment of a witness's credibility, as this improperly usurps the jury's independent fact-finding function.
The full text is available to signed-in members, including the 2 later cases that cite this judgment.
1 of the 2 citing cases carry a classified treatment. How each court treated it is available to signed-in members.