One of the statutory recognised methods in discrediting a witness is to contradict him with his previous / former statement. This is reflected in Section 155 (3) of the Indian Evidence Act which reads :
"The credit of a witness may be impeached in the following ways by the adverse party, or with the consent of the Court, by the party who calls him:
(1)…………… (2) …………
(3) by proof of former statements inconsistent with any part of his evidence which is liable to be contradicted;"
In other words, if the witness is giving contradictory statements, his credit is impeached. Consistency shows the credit worthiness of a witness and as a logical corollary, inconsistency shakes the credit.
The method of contradicting a witness with the previous statement is a practice often used by the defence to discredit a witness. This exercise is being done in the trial by marking of the contradictory statement contained in the statement given to the police under section 161 Cr.P.C.
The manner in which the omission is to be proved is a grey area. Lawyers tend to ask, as omissions, each and every trivial facts the witness deposed before the court, which does not appear in their statement to the police. The moot question is whether such a practice is permissible in law.
The effect of an omission should be a contradiction. This is explained in Section 162 of Cr.P.C in its Explanation :
"An omission to state a fact or circumstance in the statement referred to in sub- section (1) may amount to contradiction if the same appears to be significant and otherwise relevant having regard to the context in which such omission occurs and whether any omission amounts to a contradiction in the particular context shall be a question of fact."
The legal impact of discrediting the witness comes here when and only when the omission amounts to
(1) Contradiction; and it should be
(2) significant and otherwise relevant having regard to the context in which such omission occurs
This leads to two situations. The first one speaks about a "CONTRA – DICTION" For proving that there should be a former diction ( statement to the police ) that is 'contra' to the present diction ( evidence before the court)
As far as 'Omissions' are concerned, there will not be a previous 'diction' which is 'contra' to the present 'diction'. Hence there may not be a statement for the cross examiner to point out from the statement to the police officer to show that it is contra to the diction made in Court.
The question was mooted before the 6 member constitutional bench of the Supreme Court in Tahsildar Singh v. State of U.P. During the trial of a murder case, two questions were put to the witness as omissions. But the trial court disallowed them. The matter came to the Supreme Court.
Since silence before the police on an aspect during investigation was not a 'diction' there was no contra-diction before the trial court to make it an omission that amounts to contradiction . So the question was how the defence can use such omissions to contradict a witness.
The issue was resolved by the Supreme Court by pointing out 3 situations where an omission can be treated as a contradiction. The court said " though the particular statement is not expressly recorded, a statement that can be deemed to be part of that expressly recorded statement can be used for contradiction, not because it is an omission strictly so called but because it is deemed to form part of the recorded statement.
The court further held that such a fiction is permissible by construction only in the following three cases.
Para 26. ' From the foregoing discussion the following propositions emerge: … (3) though a particular statement is not expressly recorded, a statement that can be deemed to be part of that expressly recorded statement can be used for contradiction, not because it is an omission strictly so called but because it is deemed to form part of the recorded statement;
(4) such a fiction is permissible by construction only in the following three cases: (i) when a recital is necessarily implied from the recital or recitals found in the statement: illustration: in the recorded statement before the police the witness states that he saw A stabbing B at a particular point of time, but in the witness box he says that he saw A and C stabbing B at the same point of time; in the statement before the police the word "only" can be implied i. e., the witness saw A only stabbing B;
(ii) a negative aspect of a positive recital in a statement: illustration: in the recorded statement before the police the witness says that a dark man stabbed B, but in the witness box he says that a fair man stabbed B; the earlier statement must be deemed to contain the recital not only that the culprit was a dark complexioned man but also that he was not o of fair complexion; and
(iii) when the statement before the police and that before the Court cannot stand together: illustration: the witness says in the recorded statement before the police that A after stabbing B ran away by a northern lane, but in the Court he says that immediately after stabbing he ran away towards the southern lane; as he could not have run away immediately after the stabbing i. e., at the same point of time, towards the northern lane as well as towards the southern lane, if one statement is true, the other must necessarily be false.'
Hence such Omissions alone could be termed as contradictory statements to impeach the credit of the witness. The credit goes away because of the impact of those omissions, the consistency of the witness is adversely affected.
In the 2nd situation ( i.e significant and otherwise relevant having regard to the context in which such omission occurs ) the omission should be something significant and otherwise relevant having regard to the context in which that omission occurred. In other words all omissions could not be asked or proved.
This is made clear in the statute when it was redrafted in 1973. In 1959, the time when Tahsildar Singh was rendered, these words were not in Section 162. The explanation in Sec 162 Cr.P.C were added to cover up the situations in which the maker of the statement ought to have made a statement before the police had he really witnessed the incident.
For example, an eye witness to an incident that happened at night did not speak anything about the source of the light to the police. Later when he comes to the court he says that he has seen the incident in the street light. This omission should amount to a contradiction because that would have been the natural way to narrate an incident that happened at night.
At the same time it would not pass any one of the 'three tests' laid down in Tahsildar Singh. Nevertheless logically it should be treated as a material omission. Had the witness saw the incident in the street light, he would have stated so before the police and if he fails to say so, any sensible police officer would have asked him the source of light in which he claimed to have seen the incident at night. Hence the absence regarding the source of light assumes importance because it is significant and relevant regarding the context in which the said omission occurred.
Wigmore said while discussing under the head "what amounts to a Self contradiction"
"A failure to assert a fact, when it would have been natural to assert it, amounts in effect to an assertion of the non existence of the fact." 
Rationally also such omissions should be accepted as contradictions. This was discussed in Tahsildar Singh as follows: The said statement is no doubt instructive, but it cannot be pressed into service to interpret the provisions of S.162 Cr.P.C. In America, there is no provision similar to S.162 of the Code. It is not, therefore, permissible, or even possible, to interpret the provisions of a particular Act, having regard to stray observations in a text book made in a different context.
Later when Cr.P.C was redrafted in 1973 an explanation to Section 162 was added to make it clear what amounts to Omission. (This was done on the recommendation of the joint committee of the parliament dated 04.12.1972)
Many of the omissions being raised by the defence in trials are on the difference in words or on its grammatical construction. Such things cannot be treated as omissions. If the witness has stated a thing which in content is similar to the deposition before the court, that cannot be treated as an omission.
This was one of the moot questions in Tahsildar Singh. Before the police the witness said there was a lantern. Before the court he said there was a 'gas' lantern. The omission of the word 'gas' was raised during cross-examination and that was disallowed by the sessions judge. The Supreme Court ruled in favour of the decision of the Sessions judge since there was no material omission as far as the lantern was concerned.
The next issue on 'omission' was on the assertion of the witness before the trial court that while returning from the crime scene, the assailants scrutinised the faces of the deceased persons. This was not stated before the police. The discussion of the supreme court on this aspect was as follows :
" The same can be said also about the scrutiny of the faces of the dead bodies. In the statements before the police, the movements of the appellants were given. It was stated that they shot at the people and decamped with the gun of Bharat Singh. The present evidence that in the course of their pursuit, they looked at the faces of two of the dead bodies does not in any way contradict the previous versions, for the said incident would fit in with the facts contained in the earlier statements. The appellants could have shot at the audience, pursued them, taken the gun of Bharat Singh and on their way scrutinized the dead bodies. The alleged omission does not satisfy any of the principles stated by us."
This should be the way in which omissions are to be analysed, considered and proved. The trial judge, being the master of the ceremonies should be vigilant against cross-examination on insignificant omissions and contradictions.
- the omissions should be in one of three situations declared in Para 26 of Tahsildar Singh or
- it should be an omission that is significant and relevant having regard to the context in which it occurred.
- Such omissions will be significant and relevant if and only if "A failure to assert that fact, when it would have been natural to assert it, amounts in effect to an assertion of the non-existence of the fact." ( as in the case of non-mentioning about the source of light illustrated supra )
- No other omissions need be permitted to be asked or proved.
- The relevancy of such omissions have to be considered by the court using its powers under Section 136 of the Evidence Act lest it will result in wasting precious judicial time.