Evidence - Materiality. R. v. Megill
In R. v. Megill (Ont CA, 2021) the Court of Appeal set out a basic evidentiary definition of materiality:
 The circumstances in which the evidence is received in a criminal trial are well known. Relevance. Materiality. Admissibility. See R. v. Calnen, 2019 SCC 6,  1 S.C.R. 301, at para. 107, per Martin J. (dissenting, but not on this point). Likewise, the principles governing the reception of expert opinion evidence: White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23,  2 S.C.R. 182, at para. 24.. Iafolla v. Lasota
 Evidence is relevant if it has some tendency, as a matter of logic and human experience, to make the fact or proposition that it is offered to establish more likely than it would be in the absence of the evidence. We assess relevance in the context of the case as a whole and the positions of counsel: Calnen, at para. 108, per Martin J. (dissenting, but not on this point); R. v. Luciano, 2011 ONCA 89, 267 C.C.C. (3d) 16, at paras. 204-5.
 Evidence is material if what it is offered to prove or disprove is a fact in issue as determined by the allegations and the governing substantive or procedural law. Evidence that is immaterial is excluded on that ground. If erroneously admitted in a jury trial, the judge should tell the jury that they are not to consider it: Calnen, at para. 109, per Martin J. (dissenting, but not on this point); Luciano, at para. 207.
In Iafolla v. Lasota (Ont CA, 2021) the Court of Appeal defined 'material change' in a family law context:
 The discovery of the writ of execution constitutes a material change in circumstances giving rise to a variation application. The test for a “material change”, is a change that is substantial, continuing and that “if known at the time, would likely have resulted in different terms”: Willick v. Willick, 1994 CanLII 28 (SCC),  3 S.C.R. 670, at p. 688; L.M.P. v. L.S., 2011 SCC 64, at para. 32. Had the appellant’s writ of execution been known at the time of the Divorce Order, it would likely have resulted in a different order.. R v Vassel
In R v Vassel (Ont CA, 2018) the Court of Appeal provides a definition of materiality:
 Materiality. An item of evidence is material if it is offered to prove or disprove a fact in issue: Luciano, at para. 207. Whether an accused said to have committed an offence as a principal was present at the scene of the offence is a fact in issue.