Discretionary Exclusion of Evidence
- 1 General Principles
- 2 Probative Value
- 3 Prejudicial Effect
- 4 Moral and Logical Prejudice
- 5 Time Consumption
- 6 Trial Fairness
- 7 Manner of Excluding Evidence
- 8 Other Powers to Exclude Evidence
- 9 Subject-matters of Exclusionary Evidence
Even where evidence is relevant, material, and admissible, the court retains a discretionary ability to exclude evidence where the probative value of the evidence is exceeded by its prejudicial effect or where necessary to ensure trial fairness.  The discretionary power derives from both the common law and s. 24(1) of the Charter. The common-law power is protected under s. 11(d) of the charter which protects the right to a fair hearing.
The law is primarily inclusionary and will tend to admit all evidence that is logically probative of some fact in issue, subject to the rules of exclusion and exception. Where it does not fall into an exclusion or exception issues with the evidence only goes to weight.
The discretionary power allows for a cost-benefit analysis to determine if the value of the evidence to determine the case correctly "is worth the cost of its introduction to the litigation process." This will involve considering the prejudicial effect including the misleading effect and time consumption.
Burden of Proof
The onus is upon the party seeking to exclude evidence that has already been established as admissible.
To weigh probative value against prejudicial effect, it has been proposed to consider: 
- Probative value:
- the strength of the evidence
- the extent to which it supports the inferences sought to be made, and;
- the extent to which the matters it tends to prove are at issue in the proceedings.
- Prejudicial effect:
- how discreditable it is;
- the extent to which it may support an inference of guilt based solely on bad character;
- the extent to which it may confuse issues, and;
- the accused’s ability to respond to it.
In a jury setting, the judge must be scrupulous to only permit evidence that is "worthy of jury consideration" and "not whether the jury should accept and act upon the evidence."
In non-jury settings, the judge need not be as scrupulous. The judge is performing a gate-keeping function and so is capable of distinguishing prejudicial evidence. It is unreasonable that the judge is prejudiced from merely hearing evidence.
Where prejudices exist the judges are capable of self-warning of the risks of the evidence. This will often be considered sufficient precaution. A judge who is satisfied he are not prejudice should be taken at his word.
The court should consider the discretion to exclude evidence as follows:
- The judge must determine the probative value of the evidence assessing its tendency to prove a fact in issue in the case including the credibility of the witnesses.
- The judge must determine the prejudicial effect of the evidence because of its tendency to prove matters which are not in issue... or because of the risk that the jury may use the evidence improperly to prove a fact in issue.
- The judge must balance the probative value against the prejudicial effect having regard to the importance of the issues for which the evidence is legitimately offered against the risk that the jury will use it for other improper purposes, taking into account the effectiveness of any limiting instructions.
The exercise of this discretion requires substantial deference on appeal absent error in principle. The weighing between the probative value and prejudicial effect of evidence is accorded "a good deal of deference" and "absent error in principle", the decision should not be disturbed.
R v Cloutier, 1979 CanLII 25 (SCC),  2 SCR 709, 48 CCC (2d) 1, 12 C.R. (3d) 10
R v Smith, 1992 CanLII 79 (SCC),  2 SCR 915, 75 CCC (3d) 257, 15 C.R. (4th) 133
R v Moose, 2004 MBCA 176 (CanLII), 24 C.R. (6th) 246, 190 Man. R. (2d) 156
R v MF, 2009 ONCA 617 (CanLII) at para 25
R v Mohan,  2 SCR 9, 1994 CanLII 80 (S.C.C.) at pp. 20-21
R v Harrer, 1995 CanLII 70 (SCC),  3 SCR 562 at paras 23, 24, 41 and 42 - common law permits exclusion of all evidence that renders trial unfair
R v White,  2 SCR 417, 1999 CanLII 689 (SCC), at para 86
- see R v Spackman, 2009 CanLII 37920 (ON SC)
- Harrer, supra, at para 23 and 24
- R v Corbett, 1988 CanLII 80 (SCC), (1988), 41 CCC (3d) 385
R v Cyr, 2012 ONCA 919 (CanLII) at para 96, 97
Mohan, supra, at pp. 20-21
- Cyr, supra at para 97
- R v Jack 1992 CanLII 2764 (MB CA), (1992), 70 CCC (3d) 67, 15 W.C.B. (2d) 92 (Man. C.A.), at p. 86
- Sand, 2003 MBQB 76 (CanLII) at para 29
Cyr, supra at para 98 citing R v Abbey, 2009 ONCA 624 (CanLII) at para 89
see e.g. R v Virani, 2012 ABCA 155 (CanLII) at paras 13-14
TG v Nova Scotia (Community Services), 2012 NSCA 43 (CanLII) at para 75 leave to SCC denied
see R v Blea, 2012 ABCA 41 (CanLII) at para 49
R v O’Brien, 2011 SCC 29 (CanLII) at para 18,  2 SCR 485 (“The trial judge was entitled to be taken at his word.”)
- R v P. (R.) (1990), 58 CCC (3d) 334 (Ont. H.C.) at 347
R v CRB, 1990 CanLII 142 (SCC),  1 SCR 717, at p. 733
Cyr, supra at para 103
R v Shearing, 2002 SCC 58 (CanLII) at para 73
Determining the probative value of evidence includes considering the "frailties of the evidence, the inferences that may reasonably be drawn from it and the availability of other evidence to prove the same fact."
Probative value concerns the weight put on evidence and not its admissibility.
Probative value includes considering its reliability.
The reliability factor is particularly important when considering expert evidence.
Post-offence conduct of interference with witnesses will generally be found to be probative of guilt.
- R v Leitch and Jno-Baptiste, 2011 ONSC 2597 (CanLII) citing R v Pascoe 1997 CanLII 1413 (ON CA), (1997), 113 CCC (3d) 126 (Ont. C.A.)
- R v Morris, 1983 CanLII 28 (SCC),  2 SCR 190 at pp. 99-100 (C.C.C.) pp.192-3 (SCR) - cites example of documents of heroine trade found in accused's residence
- R v Cyr, 2012 ONCA 919 (CanLII) at para 97
Cyr, ibid. at para 97 citing Mohan at p. 21
R v Tran, 2001 NSCA 2 (CanLII) at para 27
R v Pillay, 2004 CanLII 9962 (ON SC) at para 21
Although the first rule of evidence is to admit all relevant evidence there are certain types of relevant evidence that should not be admitted as it will have a prejudicial effect on the fairness of the trial. It is said that there are three grounds of excluding evidence on the basis of it prejudice: "moral", "logical", and "time".
Prejudice is not simply evidence that is harmful to the defence case, but rather it is evidence that will create unfairness by misuse, over consumption of time, or distraction/confusion of issues. The impact will effect "fairness and the integrity of the proceedings"
All judges have a discretion to exclude any evidence on the basis that its prejudicial effect will out-weigh the probative value.
Where evidence is relevant to one count but irrelevant and possibly prejudicial to another count, the court may still admit the evidence but provide a limiting instruction to the jury on the limited use of the evidence.
When the evidence is called by the defence the balance between probative value and prejudicial effect is weighed further in the side of admission. A judge should only exclude evidence where the prejudicial effect "substantially outweighs" the probative value.
When dealing with a jury we must presume that limiting instructions and cautions will be followed and the evidence will be "confined within its proper bounds".
In review, the absence of objection will be a factor in considering if the evidence is significantly prejudicial.
- R v Seaboyer, 1991 CanLII 76 (SCC),  2 SCR 577, 66 CCC (3d) 321 (S.C.C.) at 390 (CCC)
R v Collins, 2001 CanLII 24124 (ON CA), (2001), 160 CCC (3d) 85, 150 O.A.C. 220 (Ont. C.A.), at para 19
R v Tran, 2001 NSCA 2 (CanLII) at para 28 - the fact that the evidence suggests guilt does not make it prejudicial
- R v Mohan 1994 CanLII 80 (S.C.C.), (1994) 29 C.R. (4th) 243 (S.C.C.)
- R v Cote, 2003 NBCA 38 (CanLII), (2003) 176 CCC (3d) 89
R v Shearing, 2002 SCC 58 (CanLII),  3 SCR 33
R v Clarke, 1998 CanLII 14604 (ON CA)
R v Cyr, 2012 ONCA 919 (CanLII) at para 99
R v Corbett, 1988 CanLII 80 (SCC),  1 SCR 670, at pp. 692-693
R v Jaw, 2009 SCC 42 (CanLII),  3 SCR 26 at para 44, citing R v Jacquard, 1997 CanLII 374 (SCC),  1 SCR 314 at paras 37-38
R v Daley, 2007 SCC 53 (CanLII),  3 SCR 523 at para 58
Moral and Logical Prejudice
First, there is evidence of moral prejudice which has the potential of creating outrage in the jury and could influence them to make their decision based on emotion. For example, a jury may get the urge to punish an accused for past bad acts even though they are not at issue in the trial. Second, there are logical prejudices that suggest to the jury to make improper inferences, such as relating the accused race with a particular disposition.
In a non-jury setting, concerns of reasoning prejudice and moral prejudice are lessened.
Prejudice arises from evidence that consumes too much time and resources. The trier-of-fact should not have their time wasted with minor evidence that will waste their time and confuse them from the real issues.
The time consumption should be commensurate to its value.
- R v Cyr, 2012 ONCA 919 (CanLII) at para 97
There is common law authority to exclude relevant and material evidence where it would render the proceedings unfair. This power is ingrained in section 11(d) of the Charter. This can involve either excluding the evidence or simply limiting its use.
The conduct of the trial, including the admission of evidence, should "not result in the trial being unfair because the accused has been denied a full opportunity to prepare his case, challenge and answer the Crown’s case." 
When considering hearsay tendered by accused the judge may relax the rules of admissibility in order to prevent a miscarriage of justice. This preferred treatment is due to the liberty interests at stake.
An accused is not entitled to a perfect trial, only a fair one.
R v Harrer, 1995 CanLII 70 (SCC),  3 SCR 562, at paras 21, 23, 41, and 42
R v White, 1999 CanLII 689 (SCC),  2 SCR 417, at para 86
- Harrer, supra at paras 23-24
Al-Shammari, 2016 ONCA 614 (CanLII) at para 39 - judge limited use of prior statement in cross examination to credibility assessment only and not truth of its contents
- R v Albright 1987 CanLII 26 (SCC),  2 S. C. R. 383 at para 26
- Paciocco and Stuesser, The Law of Evidence, Sixth Edition, at page 118
R v Khan, 2001 SCC 86 (CanLII)
R v Cai, 2012 ABCA 157 (CanLII),  A.J. No. 1521 (C.A.)
Crown Splitting its Case
As a general rule, the Crown will not be permitted to "split its case". It must "produce and enter in its own case all the clearly relevant evidence it has, or that it intends to rely upon, to establish its case".
This rule should be applied to evidence that is "clearly relevant-not marginally, minimally or doubtfully relevant".
This will sometimes be raised to prohibit the Crown from cross-examining a defence witness or the accused on a prior statement.
Manner of Excluding Evidence
Editing Recorded Statements
It is not always the case that the entirety of the evidence being admitted will be excluded. Statements—written, audio or video recorded—often include a combination of admissible and excludable evidence. The judge must then edit out the offending portions before it can be admitted into evidence.
It is the judge's discretion whether to edit out portions of a statement as irrelevant or prejudicial against a co-accused.
The judge is permitted to edit out probative evidence where the prejudicial effect is greater.
Editing "must not change the meaning of the statement in a material manner" through removal of an inculpatory or exculpatory evidence.
Other Powers to Exclude Evidence
- Exclusion of Evidence under s. 24(2) of the Charter
- Trial Management Power - judges also have the power to exclude evidence under its authority over trial management 
- Disclosure - exclusion of evidence can be used as a remedy for late disclosure
- R v Spackman, 2012 ONCA 905 (CanLII) at para 104 per Watt J