283.
—(1) A court may, on its own motion or on the application of the prosecution or the defence, at the close of the case for the defence, or at the end of any proceeding under this Code, summon a person as a witness or examine a person in attendance as a witness, whether or not summoned, or recall and re-examine a person already examined.
(2) The court must summon and examine or recall and re-examine such a person if it thinks his evidence is essential to making a just decision in the case.
(3) The exercise by a court of its power under subsection (1) is not a ground for appeal, or for revision, unless the appellant, or the applicant, as the case may be, shows that the examination has led to a failure of justice.