McInroy et al. v. The Queen,  1 S.C.R. 588:
Section 9(2) is not concerned with the cross-examination of an adverse witness. That subsection confers a discretion on a trial judge where the party producing a witness alleges that the witness has made, at another time, a written statement inconsistent with the evidence being given at the trial. The discretion is to permit, without proof that the witness is adverse, cross-examination as to the statement.
The task of the trial judge was to determine whether Mrs. St. Germaine's testimony was inconsistent with her statement to the police. In my opinion he was properly entitled to conclude that it was. At trial Mrs. St. Germaine swore that she could not recall any part of the conversation with McInroy in the kitchen of her house on the night of the killing, although only some seven months earlier she had given to the police, in her written statement, the details of that conversation, including McInroy's admission that he was the murderer. If her statement at trial as to her recollection was true, inconsistency would not arise, but the trial judge saw Mrs. St. Germaine and heard her evidence on the voir dire. It was quite open to him to conclude that she was lying about her recollection and to form his own conclusions as to why she was refusing to testify as to her true recollection. Chief Justice Farris says in terms that "the trial judge clearly did not believe her when she said she had a lack of recall". This being so there was evidence of an inconsistency between what she said at the trial, i.e. that she had no recollection of a conversation, and what was contained in her written statement, i.e. a detailed recollection of it.
In Wolf v. The Queen, this Court upheld a conviction for perjury against a person who had been the complainant on a charge of unlawfully causing bodily harm. He had given a signed statement to the police in connection with that charge. At the preliminary hearing he said that he could not remember the events described in the statement. The issue before this Court was as to whether his evidence at the preliminary hearing was given "with intent to mislead" within s. 120 of the Criminal Code. This Court held that the case was not one of mere error, honestly made, but that the circumstances justified the conclusion that the failure of memory was dishonest and deliberately asserted to prevent the Court from arriving at a decision on credible evidence.
The granting of the Crown's application was a matter for the sole discretion of the trial judge and in my view he had adequate grounds for exercising that discretion as he did. Having granted the application the Crown was entitled to cross-examine Mrs. St. Germaine before the jury. The trial judge was careful to explain, in the passage I have already quoted, the limited extent to which that cross-examination might be considered by the jury.