No obligation to raise a matter: No obligation to raise a matter: Where it is perfectly clear that [the witness] has had full notice before hand that there is an intention to impeach the credibility of the story which he is telling …all I am saying is that it will not do to impeach the credibility of a witness upon a matter on which he has not had any opportunity of giving an explanation by reason of there having been no suggestion whatever in the course of the case that his story is not accepted. Where it is perfectly clear that [the witness] has had full notice before hand that there is an intention to impeach the credibility of the story which he is telling …all I am saying is that it will not do to impeach the credibility of a witness upon a matter on which he has not had any opportunity of giving an explanation by reason of there having been no suggestion whatever in the course of the case that his story is not accepted.
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