Counsel are not permitted to personalize their final arguments by providing opinion evidence or by drawing upon information that is not part of the admissible record. When counsel start injecting their personal knowledge or judgments into their submissions, they are acting as a witness rather than an advocate.
When drafting your final submissions it may be helpful to remember that:
Your personal views about the evidence are not relevant. Instead of saying: “I believe” or “I think”, say “The Defence submits that…”;
Your factual submissions must be grounded in the evidentiary record, not your personal knowledge; and
The spotlight is on the governing law and the evidentiary record, not on you.
R. v. Tomlinson, 2014 ONCA 158 at para. 96:
…counsel, whether prosecuting or defending, are not permitted to give evidence in their closing submissions: R. v. Smith (1997), 120 C.C.C. (3d) 500 (Ont. C.A.), at para. 26. This prohibition includes providing an explanation, not otherwise in evidence, for the failure of an accused to testify. (emphasis in original)
R. v. Boudreau, 2012 ONCA 830 at para. 16:
…The Crown must not … express personal opinions about either the evidence or the veracity of a witness…
R. v. Browne, 2017 ONSC 5796 at para. 58:
…If…counsel has given evidence, a trial judge has a duty to correct the…transgression.