R v. A.T., 2015 ONCA 65:
 The Crown occupies a special position in the prosecution of criminal offences, which "excludes any notion of winning or losing" and "must always be characterized by moderation and impartiality": R. v. Boucher,  S.C.R. 16, per Rand J., at p. 24 and Taschereau J. (in translation), at p. 21. Crown counsel "must limit his or her means of persuasion to facts found in the evidence presented to the jury": R. v. Rose,  3 S.C.R. 262, at para. 107.
 As this court summarized in R. v. Mallory, 2007 ONCA 46, 217 C.C.C. (3d) 266, at para. 340, Crown counsel in the closing address should not "engage in inflammatory rhetoric, demeaning commentary or sarcasm, or legally impermissible submissions that effectively undermine a requisite degree of fairness".
 In R. v. B.(R.B.), 2001 BCCA 14, 152 C.C.C. (3d) 437, the British Columbia Court of Appeal discussed, at para. 15, the rationale for holding Crown counsel to this standard:
It takes no skill to whip up feelings against the accused in a case like this and it threatens the integrity of the trial. Applying opprobrious labels to the accused, as was done here, does nothing to advance the case; instead it cheapens the dignified position that the Crown should occupy in criminal law.
 When improper comments by Crown counsel are sufficiently prejudicial, a trial judge has a duty to intervene, and a failure to do so will constitute an error of law: R. v. Romeo,  1 S.C.R. 86, at p. 95; R. v. Michaud,  2 S.C.R. 458, at para. 2. The Supreme Court affirmed in Rose, at para. 127, that "where the trial judge fails to redress properly the harm caused by a clearly inflammatory, unfair or significantly inaccurate jury address, a new trial could well be ordered": Rose, at para. 127.
 A failure by defence counsel to object to improper remarks by Crown counsel is not a bar to a successful appeal: R. v. Ferguson (2000), 142 C.C.C. (3d) 353 (Ont. C.A.) at paras. 38, 92, reversed on other grounds, 2001 SCC 6,  1 S.C.R. 281; R. v. Angelis, 2013 ONCA 70, 296 C.C.C. (3d) 143, at para. 61; R. v. Chambers,  2 S.C.R. 1293, at pp. 1308-1309. As Doherty J.A. explained, "[a] legal error remains a legal error even if counsel does not object or even supports the erroneous instruction": R. v. Polimac, 2010 ONCA 346, 254 C.C.C. (3d) 359, at para. 97, leave to appeal refused,  S.C.C.A. No. 263.
 It does not automatically follow, however, that a new trial will be ordered when the Crown makes improper comments during a closing address, even where the remarks are not corrected. The question is whether, in the context of the entire trial, the remarks and the trial judge's response or failure to respond caused a substantial wrong or miscarriage of justice: R. v. Romeo,  1 S.C.R. 86, at p. 95.