Notional even-handedness?

Who can more easily adduce hearsay evidence – the prosecution or the defence? Or are they equal?

In Morgan v R (criticised here recently) the majority of the Supreme Court held that the Crown could adduce evidence that the accused when in a cell had confessed to his cell-mate who was now a hostile witness. This hostility was the route through which the evidence came in, but in reality the position was the same as if a reliable witness had been called to say that the cell-mate had previously said that the accused had confessed. This is, in effect, like the use of a "notional witness" who gives hearsay evidence.

One would think, by analogy, that the defence could call a reliable witness to say that another person – not the present accused - had confessed. But in R v Key [2010] NZCA 115 (31 March 2010) the Court of Appeal refused to allow the defence to ask a police officer whether he had made a note of his conversation with the mother of a witness, who said that the witness had confessed to her. The witness in evidence had denied making such a confession to his mother, and the mother was not available to testify. The reason the evidence from the police officer was not admissible was because there was insufficient assurance of reliability as is required by s 18(1)(a) Evidence Act 2006.

It seems odd that there was insufficient assurance of reliability where (1) a mother told the police what her son had said; (2) where the son had spoken against self-interest; (3) where a police officer investigating the case noted the conversation. Where were the sources of error in these against-interest communications? Furthermore, in contrast to Morgan, in Key the confession contained information that only a guilty person would know and that was corroborated by other witnesses.

I was not involved in either case, and it may be that on careful scrutiny of the evidence Key can be justified. But these are the sorts of cases that make observers most anxious about the even-handedness of the application of the law.