Section 29: Supplemental powers of court.

In the exercise of its appellate jurisdiction, the Supreme Court 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; and
(b) order any of the witnesses who would have been compellable witnesses at the trial to attend and be examined before the Court, whether they were or were not called at the trial, or order the examination of any such witnesses to be conducted in manner provided by rules of court, or, in the absence of rules of court making provision on that behalf, as it may direct, before any judge of the Court or before any officer of the Court or other person appointed by the Court for the purpose, and allow the admission of any depositions so taken as evidence before the Court; and
(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 conveniently be conducted before the Court, order the reference of the question in 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 of any such commissioner appointed by the Court, 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 any other powers which may for the time being be prescribed by rules of court and issue any warrants necessary for enforcing the orders or sentence of the Court:
Provided that in no case shall any sentence be increased by reason of or in consideration of any evidence that was not given at the trial.