Acceptance of Evidence
In a criminal hearing, a trier of fact will generally determine facts based solely on admissible evidence given through witnesses, physical exhibits, and admissions by the parties.The adversarial system depneds on production of evidence by parties in order to guarantee "its sufficiency and trustworthiness".
Evidence provides a means of allowing facts to be proved for the purpose of deciding issues in litigation. The trier of fact may only consider evidence that is admissible, material and relevant. Even then, evidence that creates undue prejudice may nonetheless be ruled inadmissible.
The purpose of the rules of evidence are to permit the trier-of-fact to "get at the truth and properly determine the issues".
A judge may only base a decision on "evidence presented at trial, except where judicial notice may be taken" or any other findings permitted under the Code.
The party seeking to tender evidence must meet the necessary threshold requirements of admissibliity before it can be considered.
Requirements Before Acceptance
For a trier-of-fact to receive evidence, the judge must be satisfied that the evidence is:
- not barred by rules of admissibility, and
- not subject to discretionary exclusion.
Once relevance and materiality is established, the evidence is admissible except where captured by an exclusionary rule.
While the rules of evidence always apply to criminal matters, courts are entitled to be flexible with the evidence rules in order to "prevent miscarriages of justice".
The admissibility of evidence is a question of law and is reviewable on a standard of correctness.
R v VHM, 2004 NBCA 72 (CanLII) citing McWilliams, Canadian Criminal Evidence 4th Ed. (Aurora, Ont. Canada Law Book Inc, 2004 at para 23:10)
R v Seaboyer; R v Gayme,  2 SCR 577, 1991 CanLII 76 (SCC) ("fundamental to our system of justice that the rules of evidence should permit the judge and jury to get at the truth and properly determine the issues."
R v Bornyk, 2015 BCCA 28 (CanLII) at para 8 - judge improperly relied on academic articles not in evidence
see also R v RSM, 1999 BCCA 218 (CanLII) at para 20
R v Cloutier, 2011 ONCA 484 (CanLII)
R v Johnson,  OJ No 4153 at para 90
- R v Candir, 2009 ONCA 915 (CanLII), per Watt J.A. at para 46 - requires evidence be (1) relevant (2) material (3) admissible
R v Cyr, 2012 ONCA 919 (CanLII) per Watt JA at para 96 - sets out the four points of admissibility
see also R v Zeolkowski, 1989 CanLII 72 (SCC),  1 SCR 1378
R v Watson, 1996 CanLII 4008 (ON CA), 108 CCC (3d) 310, (Ont. C.A.)
see Zeolkowski, supra
R. v. Watson, 1996 CanLII 4008 (ON CA), 108 C.C.C. (3d) 310, (Ont. C.A.)
R v Muise, 2013 NSSC 141 (CanLII) at para 47 aff'd on other grounds 2015 NSCA 54
R v Muise, 2013 NSCA 81 (CanLII) at para 27
R v Howe, 2016 NSSC 140 (CanLII) at para 7
- R v Simpson, 1977 CanLII 1142 (ON CA), (1977), 35 CCC (2d) 337 (Ont. C.A.)
R v Starr,  2 SCR 144, 2000 SCC 40 (CanLII), at para 184;
R v Harper, 1982 CanLII 11 (SCC),  1 SCR 2
Evidence must be relevant before it can be admissible, irrelevant evidence must be excluded. 
Relevancy is evidence that tends, "as a matter of logic and human experience", to make a proposition more likely to be true.
Relevancy requires that there be a nexus between facts. The evidence should permit an inference that if one fact exists the other must as well. Relevance is "assessed in the context of the entire case and the positions of counsel. It requires a determination whether, as a matter of human experience and logic, the existence of a particular fact, directly or indirectly, makes the existence or non-existence of a material fact more probable than it would be otherwise".
Certain evidence does not cease to be relevant or become irrelevant simply because it can support more than one inference. 
Relevance is sometimes divided into 1) logical relevance and 2) legal relevance. Logical relevance refers to the connection between two facts. Legal relevance is the cost/benefit analysis of the admission of evidence on the basis of: 
- the probative value outweighing prejudicial effect;
- the "inordinate amount of time which is not commensurate with its value";
- its "misleading" effect ... is "out of proportion to its reliability".
All relevant evidence is admissible exception for the discretionary power of the judge to exclude evidence that is unduly prejudicial, misleading , or confusing.
The relevance of evidence is a question of law and is reviewable on a standard of correctness.
- Hollington v Hewthorn & Co. Ltd.,  K.B. 587 (C.A.), at p. 594 (“all evidence that is relevant to an issue is admissible, while all that is irrelevant is excluded”)
R v Cloutier, 1979 CanLII 25 (SCC), (1979), 48 CCC (2d) 1 (S.C.C.)
R v Zeolkowski, 1989 CanLII 72 (SCC),  1 SCR 1378, 50 C.C.C (3d) 566
R v J.-L.J.,  2 SCR 600, 2000 SCC 51 (CanLII) ("Evidence is relevant “where it has some tendency as a matter of logic and human experience to make the proposition for which it is advanced more likely than that proposition would appear to be in the absence of that evidence” (D. M. Paciocco and L. Stuesser, The Law of Evidence (1996), at p. 19).")
R v Arp,  3 SCR 339, 1998 CanLII 769 (SCC)
- Cloutier, supra
Cloutier, supra at p. 27 and referenced in Watt's Manual of Criminal Evidence, 2010, (Thomson Carswell: Toronto, 2008) at Section 3.0
R v Sims (BCCA) 1994 CanLII 1298 (BC CA), (1994), 87 CCC (3d) 402 at pp. 420-27 - relevance determined by the context of the entire case and taking into account Crown and defence
- R v Underwood 2002 ABCA 310 (CanLII) at para 25
- R v Mohan, 1994 CanLII 80 (SCC),  2 SCR 9
R v Morris, 1983 CanLII 28 (SCC),  2 SCR 190 - discusses requirement of "logically probative" evidence
R v Corbett, 1988 CanLII 80 (SCC),  1 SCR 670, (1988), 41 CCC (3d) 385
See also Discretionary Exclusion of Evidence
- Mohan, supra at para 18
Evidence must be material to be admissible. Material evidence refers to evidence that contributes to proving a fact that is of consequence to the trial. That is, there must be a relationship between the evidence and a legal issue put to the court. Material evidence can include not only evidence establishing a fact that is necessary to prove an essential element of the case or it can be a fact that refutes or negates an essential element or any other relevant evidence.
This should be treated separately from the question of admissibility and relevance.
As this diagram shows, materiality represents the proximity of a fact to an essential element to be proven as part of the Crown's case. Fact A is material where it is supports some Fact B that, if made out, establishes some legal requirement at issue.
Relevancy Limited by Materiality
Relevancy can be chained together establishing a link between several propositions, but they must always link back to establishing or negating a material issue.
Take the somewhat contrived example of a domestic homicide where an essential element is identity. The husband of the victim is found nearby at a friend's house shortly after time of death. It was raining the day of the murder and no vehicle transportation was available to the husband. Evidence related to whether the accused's clothes or body was wet is relevant to the proposition that he was at the location of the murder while it was raining and then left, which is material evidence to the question of whether he was the one who committed the murder. We can extend the "chain" of relevancy by looking at the evidence (e.g. eye-witness or photographic) of whether there were any umbrellas in the friend's house that may explain why the husband appeared dry. The chain of relevancy will likely be broken if it extends even further to present evidence showing how often it rains in the area and how conscientious the friend must be and so must have owned an umbrella in his house. Such evidence is distant and remote enough to the essential question that it may not be permitted on the basis that the prejudicial effect (time wasting) outweighs the probative value (weak chain of logic).
- R v Gill (1987) 39 CCC (3d) 506 (MBCA)(*no link)
- R v Bernardi (1974), 20 CCC (2d) 523 (ONCA)(*no link) leave to SCC refused
Rules of Admissibility
Real evidence that has been proven to be relevant and material are prima facie admissible regardless of whether the investigative conduct to seize the evidence was lawful or not.
Much of the entirety of the rules of evidence concern the question of what is admissible evidence. As such, admissibility of evidence can be better understood as evidence that is not prohibited by an exclusionary rules. To name frequently encountered rules of exclusion include:
- Witness competence
- Conduct on occasions separate from the offence
- Illegally obtained evidence
See also R v Zeolkowski (1987) 333 CCC 231 (*no link)
R v Hawkes (1915) 25 CCC 29 (ABCA) (*no link)
R v FFB,  1 SCR 697, 1993 CanLII 167 (SCC) at page 136 ("The basic rule in Canada is that all relevant evidence is admissible unless it is barred by a specific exclusionary rule.")
R v Collins, 2001 CanLII 24124 (ON CA) at para 18, 19
R v Cyr, 2012 ONCA 919 (CanLII) at para 116
R v Morris, 1983 CanLII 28 (SCC),  2 SCR 190, - adopting Thayer's approach to the admission of evidence
- R v Sadikov, 2014 ONCA 72 (CanLII) at para 34
Discretionary Exclusion of Evidence
In addition to the application of specific rules exclusionary rules of evidence, there is a residual common law discretion to exclude any evidence where the prejudicial effect of the evidence outweighs the probative value.
Whenever evidence is tendered, a judge may ask counsel for the purpose of tendering the evidence and counsel should give a response.
The judge has a duty to exclude all inadmissible evidence, regardless of whether the issue is raised by counsel.
- Cox, Criminal Evidence Handbook, 2nd edition, at p. 4
R v D. (L.E.), 1989 CanLII 74 (SCC),  2 SCR 111
R v Ambrose (1975), 25 CCC (2d) 90 (NBSC, Div. App.), aff'd 1976 CanLII 201 (SCC) ,  2 SCR 717
see also Canadian Criminal Evidence, 3rd ed.,P.K. McWilliams states in paragraph 3:10410 cited in R v Bourque, 1991 CanLII 2607 (NS CA)