A Division Bench of the Supreme Court held as follows regarding the purpose and import of Section 313 of Cr.P.C.,

From Para 15,

15. What follows from these authorities may briefly be summarized thus:
a. section 313, Cr. P.C. [clause (b) of sub-section 1] is a valuable safeguard in the trial process for the accused to establish his innocence;
b. section 313, which is intended to ensure a direct dialogue between the court and the accused, casts a mandatory duty on the court to question the accused generally on the case for the purpose of enabling him to personally explain any circumstances appearing in the evidence against him;
c. when questioned, the accused may not admit his involvement at all and choose to flatly deny or outrightly repudiate whatever is put to him by the court;
d. the accused may even admit or own incriminating circumstances adduced against him to adopt legally recognized defences;
e. an accused can make a statement without fear of being cross-examined by the prosecution or the latter having any right to cross-examine him;
f. the explanations that an accused may furnish cannot be considered in isolation but has to be considered in conjunction with the evidence adduced by the prosecution and, therefore, no conviction can be premised solely on the basis of the section 313 statement(s);
g. statements of the accused in course of examination under section 313, since not on oath, do not constitute evidence under section 3 of the Evidence Act, yet, the answers given are relevant for finding the truth and examining the veracity of the prosecution case;
h. statement(s) of the accused cannot be dissected to rely on the inculpatory part and ignore the exculpatory part and has/have to be read in the whole, inter alia, to test the authenticity of the exculpatory nature of admission;
i. if the accused takes a defence and proffers any alternate version of events or interpretation, the court has to carefully analyze and consider his statements; and
j. any failure to consider the accused’s explanation of incriminating circumstances, in a given case, may vitiate the trial and/or endanger the conviction.

From Para 16,

16. Bearing the above well-settled principles in mind, every criminal court proceeding under clause (b) of sub-section (1) of section 313 has to shoulder the onerous responsibility of scanning the evidence after the prosecution closes its case, to trace the incriminating circumstances in the evidence against the accused and to prepare relevant questions to extend opportunity to the accused to explain any such circumstance in the evidence that could be used against him. Prior to the amendment of section 313 in 2009, the courts alone had to perform this task. Instances of interference with convictions by courts of appeal on the ground of failure of the trial court to frame relevant questions and to put the same to the accused were not rare. For toning up the criminal justice system and ensuring a fair and speedy trial, with emphasis on cutting down delays, the Parliament amended section 313 in 2009 and inserted sub-section (5), thereby enabling the court to take the assistance of the Public Prosecutor and Defence Counsel in preparing such questions [the first part of sub-section (5)]. Ideally, with such assistance (which has to be real and not sham to make the effort effective and meaningful), one would tend to believe that the courts probably are now better equipped to diligently prepare the relevant questions, lest there be any infirmity. However, judicial experience has shown that more often than not, the time and effort behind such an exercise put in by the trial court does not achieve the desired result. This is because either the accused elects to come forward with evasive denials or answers questions with stereotypes like ‘false’, ‘I don’t know’, ‘incorrect’, etc. Many a time, this does more harm than good to the cause of the accused. For instance, if facts within the special knowledge of the accused are not
satisfactorily explained, that could be a factor against the accused. Though such factor by itself is not conclusive of guilt, it becomes relevant while considering the totality of the circumstances. A proper explanation of one’s conduct or a version different from the prosecution version, without being obliged to face cross-examination, could provide the necessary hint or clue for the court to have a different perspective and solve the problem before it. The exercise under section 313 instead of being ritualistic ought to be realistic in the sense that it should be the means for securing the ends of justice; instead of an aimless effort, the means towards the end should be purposeful. Indeed, it is optional for the accused to explain the circumstances put to him under section 313, but the safeguard provided by it and the valuable right that it envisions, if availed of or exercised, could prove decisive and have an effect on the final outcome, which would in effect promote utility of the exercise rather than its futility.

From Para 17,

17. Once a written statement is filed by the accused under subsection (5) of section 313, Cr. P.C. and the court marks it as an exhibit, such statement must be treated as part of the accused’s statement under sub-section (1) read with sub-section (4) thereof. In view of the latter sub-section, the written statement has to be considered in the light of the evidence led by the prosecution to appreciate the truthfulness or otherwise of such case and the contents of such statement weighed with the probabilities of the case either in favour of the accused or against him.