As a general rule, a recording or transcript of prior testimony cannot be advanced as evidence at trial unless the declarant personally attends and testifies. This is because opposing counsel would not have the opportunity to cross-examine the witness if their prior testimony was introduced as evidence.
There is, however, an exception to this hearsay rule that allows prior testimony to be introduced as evidence when certain conditions are met. Prior testimony may be admissible where the Crown is unable to get the evidence in any other way. If there is another avenue for the Crown to introduce the particular piece of evidence, the prior testimony will be considered hearsay and will be inadmissible. To be admissible, the prior testimony must have also been adduced in a matter that is substantially the same as the current matter. The parties and main issues must be mostly the same in both matters. Finally, before the evidence can be admitted under this exception to the hearsay rule, there must have been a sufficient opportunity to cross-examine the declarant when the testimony was originally given. The individual cross-examining the declarant must have had a similar interest in the matter as the accused in the current case.
Person A is on trial for a string of violent robberies. Person C witnessed the robberies and testified at trial against person B, who also participated in the robberies. The Crown in person A’s trial wishes to call person C as a witness, however, person C has since been diagnosed with dementia and is no longer capable of testifying. Person C’s testimony from person B’s trial may be introduced as evidence against person A at trial because the evidence is not otherwise available, the issues and people involved in both trials are mostly the same, and the interests of person B’s lawyer, who cross-examined person C, are sustainably the same as the interests of person A and their lawyer.