Canadian Criminal Law/Continuity
The Crown has the duty to prove an exhibit's integrity beyond a reasonable doubt. It must be shown that the items in evidence before the court in trial were the same items seized during the investigation. So for example, the Crown must prove that the drugs presented in court are the same that were seized at the scene of the investigation. Where the proof of the item is part of an essential element of the case, such as in a drug possession case, then it should be proven beyond a reasonable doubt. Gaps in continuity are not fatal unless they raise a reasonable doubt about the exhibit’s integrity.
However, it has been said that generally speaking, "continuity of an exhibit goes to weight, not to admissibility." A party who cannot "prove absolute continuous possession...would not preclude admissibility".
There is no specific requirement to that the crown lead continuity evidence. Nor does every person in the chain of possession need to testify. The evidence of continuity should be lead where there is potential evidence before the court, by direct or circumstantial evidence or by inference, that may raise doubt as to the continuity. Even where gaps may raise a reasonable doubt about the item in court is the same seized initially by police, it may still be admissible and the doubt will simply go do weight.  For example, problems with continuity and integrity of recordings generally goes to their weight not the admissibility of the contents of the recordings.
The evidence seized by police will be catalogued and given identifying numbers. These numbers should remain consistent throughout the case. So whether the items are sent to a lab for analysis, they will always be identifiable as the same once they are presented in court. Any changes of the numbering system should be recorded and explained in court. Failure to properly track the exhibits by their identifying numbers may raise doubt as to their continuity.
- R v Oracheski, (1979) 48 CCC (2d) 217 (ABCA)
R v DeGraaf 1981 CanLII 343, (1981), 60 CCC (2d) 315 (BCCA)
c.f. R v Murphy 2011 NSCA 54 at para. 41 citing R v Jeffrey  AJ. 639
- R v West, 2010 NSCA 16 at para. 130
see also R v Krole 1975 CarswellMan 119 at para. 27
- Krole at para. 27
- R. v. Adam 2006 BCSC 1430 at page 7
- R. v. Adam 2006 BCSC 1430 (2007) BCWLD 1987 at page 7
R. v. Andrade, (1985), 6 O.A.C. 345, 18 C.C.C. (3d) 41 (Ont. C.A.)
- R. v. Meer,  A.J. No. 1123 (Q.B.), 2010 ABQB 617 at 16
- e.g. R. v. Martin, 2008 ONCJ 601 at 16