Demeanour Evidence'Demeanour evidence' means a witness' observations of the emotional state of a person that they are testifying about. 'Witness demeanour' (a separate topic) means a witness' demeanour while giving testimony.
. R. v. Staples
In R. v. Staples (Ont CA, 2022) the Court of Appeal briefly considered demeanour evidence:
 The starting point is that although its admission may be somewhat rare, there is no bar to the admission of demeanour evidence. It may be admitted where a witness has a basis for believing that an accused’s demeanour was unusual: R. v. Trotta (2004), 2004 CanLII 34722 (ON CA), 190 C.C.C. (3d) 199 (Ont. C.A.), rev’d on other grounds, 2007 SCC 49,  3 S.C.R. 453; R. v. Short, 2018 ONCA 1, 358 C.C.C. (3d) 337, at para. 54.