Questions in cross-examination that ask an accused person to explain why a complainant would fabricate his or her allegations are improper.
R. v. Rose, 2001 CanLII 24079 (ON CA), at para. 27: It is improper to call upon an accused to comment on the credibility of his accusers.
See also R. v. L.L., 2009 ONCA 413 (CanLII), at paras. 15-16.
The concern with this line of questioning is two-fold:
1. It is unfair to ask an accused to speculate about a witness’s motives;
2. These questions risk shifting the burden of proof. The burden is on the Crown to prove beyond a reasonable doubt that a complainant’s allegations are true. Yet questions to an accused about a complainant’s motives may cause the trier of fact to focus on whether the accused can provide an explanation for why a complainant would make false allegations, and find the accused guilty if a credible explanation is not forthcoming.
R. v. T.M., 2014 ONCA 854, at paras. 37-38.
The fact that it may be appropriate for the police as part of an investigation to ask the accused to explain why the complainant made the allegations against him does not mean that portions of an accused’s statement in which such questions are asked are properly admissible at trial.
R. v. L.(L.), 2009 ONCA 413, 96 O.R. (3d) 412, at para. 17.
R. v. F.(C.),  CanLII 623 (Ont. C.A.).
The Crown is entitled to cross-examine on inconsistencies between what the accused stated to police as the complainant s motive for accusing him and what he later states in examination-in-chief.
R. v. M.S., 2019 ONCA 869, at para. 8.
Stuart O’Connell, O’Connell Law Group (All rights reserved to author).