Discharge u/s239 and s311 of crpc

S. 243(2) CrPC | Accused Can't Summon Prosecution Witness Who He Had Cross-Examined Unless Magistrate Satisfied It Is Essential: 

No bar to examine discharged prosecution witness as defense witness: Supreme Court. Supreme Court permitted the appellant to examine the prosecution witness as defense witness and kept it open for the prosecution to cross-examine the said witness.

An application under section 311 Cr. P.C must not be allowed only to fill up a lacuna in the case of the prosecution, or of the defence, or to the disadvantage of the accused, or to cause serious prejudice to the defence of the accused, or to give an unfair advantage to the opposite party.

Section 311 permits any court at any stage of an enquiry, trial or other proceeding summon any person as a witness, or examined any person in attendance, though not summoned as a witness, or recall and re-examine, any person already examine; and the court shall summon and examine or recall and re-examine in such.