In a criminal trial, accused is presumed to be innocent until proved guilty beyond reasonable doubt. The Latin maxim, ‘Ei incumbit probatio qui dicit, non qui negat’ signify that the burden of proof is on prosecution, who asserts, not on accused, who denies.
In case of Woolmington vs. The Director of Public Prosecutions,  AC 462,  UKHL 1, the House of Lords reiterated following:
“Throughout the web of the English Criminal Law one golden thread is always to be seen, that it is the duty of the prosecution to prove the prisoner’s guilt subject to what I have already said as to the defence of insanity and subject also to any statutory exception. If, at the end of and on the whole of the case, there is a reasonable doubt, created by the evidence given by either the prosecution or the prisoner, as to whether the prisoner killed the deceased with a malicious intention, the prosecution has not made out the case and the prisoner is entitled to an acquittal.”
In King Emperor vs U. Damapala, (37) 24 A.I.R. 1937 Rang. 83, Full Bench of Rangoon High Court laid a proposition and answered it in following manner:
“The main proposition may be laid down simply as follows: in all criminal’ cases where there is a reasonable doubt as to the guilt of an accused person at the close of the whole of the evidence the accused is entitled to be acquitted?”
“Put shortly, the test is not ’whether the accused has proved beyond all reasonable doubt that he comes within any exception to the Indian Penal Code, but whether in setting up his defence he has established a reasonable doubt in the case for “the prosecution and has thereby earned his right to an acquittal.”
In Dahyabhai Chhaganbhai Thakker vs State of Gujarat, Criminal Appeal No. 58 of 1962, the Supreme Court stated following:
“The doctrine of burden of proof in the context of the plea of insanity may be stated in the following propositions:
(1) The prosecution must prove beyond reasonable doubt that the accused had committed the offence with the requisite mens rea, and the burden of proving that always rests on the prosecution from the beginning to the end of the trial.
(2) There is a rebuttable presumption that the accused was not insane, when he committed the crime, in the sense laid down by s. 84 of the Indian Penal Code: the accused may rebut it by placing before the court all the relevant evidence-oral, documentary or circumstantial, but the burden of proof upon him is no higher than that rests upon a party to civil proceedings.
(3) Even if the accused was not able to establish conclusively that he was, insane at the time he committed the offence, the evidence placed before the court by the accused or by the prosecution may raise a reasonable doubt in the mind of the court as regards one or more of the ingredients of the offence, including mens rea of the accused and in that case the court would be entitled to acquit the accused on the ground that the general burden of proof resting on the prosecution was not discharged.”
In case of Harbhajan Singh vs State of Punjab, Criminal Appeal No. 53 of 1951 following was stated by the Supreme Court:
“Where an accused person is called upon to prove that his case falls under an Exception, law treats the onus as discharged if the accused person succeeds “in proving a preponderance of probability.” As soon as the preponderance of probability is proved, the burden shifts to the prosecution which has still to discharge its original onus. It must be remembered that basically, the original onus never shifts and the prosecution has at all stages of the case, to prove the guilt of the accused beyond a reasonable doubt. As Phipson has observed, when the burden of an issue is upon the accused, he is not, in general, called on to prove it beyond a reasonable doubt or in default to incur a verdict of guilty; it is sufficient if he succeeds in proving a preponderance of probability, for then the burden is shifted to the prosecution which has still to discharge its original onus that never shifts, i.e., that of establishing, on the whole case, guilt beyond a reasonable doubt.”
In Rabindra Kumar Dey vs State of Orissa, Criminal Appeal No. 193 of 1971 following was held by the Supreme Court:
“On a consideration of the evidence and the circumstances we are satisfied that the appellant has been able to prove that the explanation given by him was both probable and reasonable judged by the standard of the preponderance of probabilities This being the position, it was for the prosecution to prove affirmatively in what manner the amount was misappropriated after it had been transferred from the custody of the appellant to the custody of the Nazir. Such proof is wholly lacking in this case. As the accused has given a reasonable explanation, the High Court was in error in drawing an adverse inference against him to the effect that he had misappropriated the money.”
In case of Partap vs The State Of U.P, Criminal Appeal No.- 120 of 1971, the Supreme Court stated following qua two full bench decision of Allahabad High Court (i) Parbhoo And Ors. vs Emperor, AIR 1941 All 402 (ii) Rishi Kesh Singh And Ors. vs The State, AIR 1970 All 51:
“The findings of the Trial Court on the defence version indicate that a question of law arise here which seems to have troubled several High Courts. It gave rise to two Full Bench decisions of the Allahahad High Court, the first in Parbhoo v. Emperor,(l) and the second in Rishi Kesh Singh & ors. v. the State(‘). It does not seem to have been considered in the same form by this Court. I think this is an appropriate case in which this Court could consider and decide it, and, it is because this aspect of the case was ignored by the Trial Court as well as the High Court that I consider this to be a fit case for a reconsideration of evidence and interference by this Court under Article 136 or the Constitution.”
The following was held in Partap vs The State Of U.P, Criminal Appeal No.- 120 of 1971:
“In the light of the above discussion, the conclusion is inescapable that the appellant had succeeded in establishing by a preponderance of probability, that the deceased was within a striking distance, poised for imminent attack on the appellant with a spear, when the latter fired the fatal gunshot. In such a situation, the appellant had reasonable and immediate apprehension that he would suffer death or grievous hurt if he did not fire at the deceased. Thus, the death was, in all probability, caused by the appellant in the exercise of his right of private defence.
In Vijayee Singh and ors vs State of Uttar Pradesh, Criminal Appeal No. 375-77 of 1987, the Supreme Court reiterated following:
“The accused may also show on the basis of the material a preponderance of probability in favour of his plea. If there are absolutely no circumstances at all in favour of the existence of such an exception then the rest of the enquiry does not arise in spite of a mere plea being raised. But if the accused succeeds in creating a reasonable doubt or shows preponderance of probability in favour of his plea, the obligation on his part under Section 105 gets discharged and he would be entitled to an acquittal.”
In Satya Narain Yadav vs Gajanand, Criminal Appeal No. 305 of 2001, the Supreme Court stated following:
“51. The concepts of probability, and the degrees of it, cannot obviously be expressed in terms of units to be mathematically enumerated as to how many of such units constitute proof beyond reasonable doubt. There is an unmistakable subjective element in the evaluation of the degrees of probability and the quantum of proof. Forensic probability must, in the last analysis, rest on a robust common sense and, ultimately, on the trained intuitions of the Judge. While the protection given by the criminal process to the accused persons is not to be eroded, at the same time, uninformed legitimization of trivialities would make a mockery of administration of criminal justice. This position was illuminatingly stated by Venkatachaliah, J. (as His Lordship then was) in State of U.P. v. Krishna Gopal (1988 (4) SCC 302).”
A mere plausible explanation is not expected from the accused and it must be more than a plausible explanation by way of rebuttal evidence. In other words, the defence raised by way of rebuttal evidence must be probable and capable of being accepted by the Court.
Advocate Bombay High Court