Care has to be taken not to confuse the ultimate standards of proof that the law requires before facts are found in a case, with the standards that have to be met before individual items of evidence are admissible. For example, while the Crown in a criminal case must prove the guilt of the accused beyond a reasonable doubt to secure a conviction, it need
not prove each piece of its evidence beyond a reasonable doubt for that evidence to be received. A blood-stained shirt will be admissible if there is some evidence on which a reasonable trier of fact could conclude that it was the victim’s, even if it is not established beyond a reasonable doubt that it was. The trier of fact is left to decide whether the shirt assists in proving anything, in light of all the other evidence in the case. In the end, guilt can be established beyond a reasonable doubt when all the evidence is assessed together, even though, individually, none of the pieces would establish guilt beyond a reasonable doubt. It is therefore an error of law for the judge to direct a jury to apply the ultimate burden of proof to individual items of evidence72unless that item of evidence is the only proof of an essential part of the Crown case.73While the ultimate standards of proof relate to whether facts are proved, rather than whether evidence is admissible, there are standards that do apply as preconditions to the admissibility of evidence. It would be easier if there were only one such standard, but, unfortunately, there is not. The standards of admissibility vary with different kinds of evidence, and even in some cases to the same kind of evidence. It is therefore important to consult applicable rules, using the following guidelines:
Most often there will be no rule of exclusion to consider. In such cases the only standard of admission that will apply is compliance with the basic rule - that the evidence has some tendency as a matter of human experience to advance a material inquiry. Evidence meeting this modest standard will be received unless its probative value is outweighed by the prejudice it may cause if admitted. Nothing is to be gained by complicating the matter by asking whether a particular item of evidence is relevant on the balance of probabilities or whether its probative value probably outweighs the risk of prejudice it presents. If there is a dispute, a judge will simply judge whether the evidence is worth hearing given these competing concerns.
A similar approach is taken where a party wishes to have a physical item admitted into evidence and made an exhibit in the trial.74This "real evidence" is generally admissible where it is both relevant on the
standard just described, and "authentic" - in other words, where it is, in fact, what it is purported to be. The party producing the real evidence need not establish, however, that it is probably authentic or that it is authentic beyond a reasonable doubt. It is enough if there is some evidence on which a reasonable trier of fact could conclude that the item is authentic.
Many of the rules of evidence about to be examined have "factual triggers." In other words, these rules outline one or more factual...