(1)  For the purposes of this chapter the Court may, if it thinks it necessary or expedient in the interests of justice –

(a) order the production of any document, exhibit, or other thing connected with the proceedings;

(ab) order a person convicted, or a person who is a respondent to a prosecution appeal, to attend before the Court on the hearing of an appeal in relation to the person or to receive judgment in relation to the appeal;

(b) order any persons 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 any such persons to be examined before any judge of the Court, or before any officer of the Court, or justice, or other person appointed by the Court for the purpose, and admit any depositions so taken as evidence;

(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 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 application.

(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, be conveniently conducted before the Court, refer the question for inquiry and report to a commissioner appointed by the Court, and act upon the report of such commissioner so far as the Court thinks fit; and

(e) appoint any person with special expert knowledge to act as assessor to the Court in any case in which it appears to the Court that such special knowledge is required for the determination of the case –

and exercise in relation to the proceedings of the Court any other powers which may be exercised by the Supreme Court on appeals or applications in civil matters, and issue any warrant or other process necessary for enforcing the orders or sentences of the Court.

(2)  In no case shall any sentence be increased by reason of or in consideration of any evidence that was not given at the trial.