Section 26: Supplemental Powers of Court of Appeal.

In the exercise of its jurisdiction, the Court of Appeal may, if it thinks it necessary or expedient in the interest of Justice-(a) order the production of any document, exhibit, or other thing connected with the proceedings, the production of which appears to it necessary for the determination of the case;
(b) order any witnesses who would have been compellable witnesses at the trial to attend and be examined before the Court of Appeal, whether they were or were not called at the trial, or order the examination of any such witnesses to be conducted in a manner provided by rules of court, or, in the absence of rules of court making provision in that behalf, as it may direct, before any Justice of the Court of Appeal or before any officer of the Court of Appeal or other person appointed by the Court of Appeal for the purpose, and allow the admission of any depositions so taken as evidence before the Court of Appeal;
(c) receive the evidence, if tendered, of any witness (including the appellant) who is a competent but not compellable witness, and, if the appellant makes an application for the purpose, of the husband or wife of the appellant, in cases where the evidence of the husband or wife could not have been given at the trial except on such an application; and
(d) where any question arising on the appeal involves prolonged examination of documents or accounts, or any scientific or local investigation, which cannot, in the opinion of the Court of Appeal, conveniently be conducted before the Court of Appeal, order the reference of the question in the manner provided by rules of court, or in the absence of rules of court making provision in that behalf, as it may direct, for enquiry and report, to a special commissioner appointed by the Court of Appeal, and act upon the report of any such commissioner so far as it thinks fit to adopt it; and exercise in relation to the proceedings of the Court of Appeal, any other powers which may for the time being be prescribed by rules of court, and issue by any warrants necessary for enforcing the orders or sentences of the Court of Appeal:
Provided that, in no case shall a sentence be increased by reason of or in consideration of any evidence that was not given at the trial.