The Principled Exception and the Forgotten Criterion
Necessity, Reliability, Hearsay, Principled Exception, Evidence, Admissibility
The principled exception to the hearsay rule is routinely described as being settled by the "twin criteria" of necessity and reliability. In fact a third criterion is also — or at least ought to be — at play: that admitting the evidence through hearsay would not undermine any other rule of evidence. The Court has made reference to this third criterion in the past, but it has largely been ignored in both Supreme Court and lower court decisions. The recent judgement in Couture depends in a limited way on that question, and so it marks an opportunity to articulate the issue more clearly, which ought to be considered at least in all principled exception cases.
This third criterion is related to the issue of necessity. Necessity is hardly discussed in judgments, and often properly so: where a witness is dead there is little to say on the matter. And although classically "necessity" contemplated situations where a witness was dead, insane, or out of the country, it has been clear from the start that the principled exception encompassed a broader meaning. In Khan itself, where the principled exception arose, the necessity criterion was met because the child's evidence was inadmissible, rather than because the child herself was unavailable. In B. (K.G.) the court made clear that the issue was whether the particular testimony was unavailable, even if the witness was personally present. Although necessity does not mean "necessary to the prosecution's case," it is satisfied if the evidence is "reasonably necessary."
Steve Coughlan, "The Principled Exception and the Forgotten Criterion" (2007) 47 CR (6th) 61.