An accused who testifies can be cross-examined on prior inconsistent statements, assuming those statements are admissible. Cross-examination on a prior inconsistent statement may be used to impeach the credibility of the accused, or in an attempt to have the accused adopt the prior statement as true.
Prior Inconsistent Statements: Using Omissions to Police to Impeach the Accused’s Credibility
R. v. Hill, 2015 ONCA 616, at para. 43;
R. v. Paris, 2000 CanLII 17031 (ON CA),  O.J. No. 4687, at para. 41.
Omissions can be integral to the existence of material inconsistencies between two versions of events. An account of an event which leaves out important details may be viewed as inconsistent with a subsequent account that includes those details.
R. v. Hill, at para. 45.
Impeaching the Accused’s Credibility through his Omissions to Police
Generally, an accused’s exercise of his right to silence when questioned by the police cannot be used as circumstantial evidence of guilt or to impeach the credibility of the accused’s trial testimony:
The propriety of cross-examination on a prior statement made by an accused to the police turns on the purpose of the cross-examination.
If the cross-examination is designed to challenge the credibility of an accused’s testimony based on inconsistencies between that testimony and a previous version of events provided by the accused, the cross-examination is appropriate. If, however, the cross-examination invites the trier of fact to draw an adverse inference from the accused’s silence when questioned by the police, the cross-examination is inappropriate.
A trial judge can refuse or limit cross-examination on the prior statement of an accused to police when there is a legitimate concern that the cross-examination may trespass improperly on the accused’s right to silence.
R. v. Hill, at para. 46;
see for instance R. v. Shawanda, 2017 ONSC 5559.
Where defence counsel specifically asks the accused why he did not mention an important detail in his account to police, the Crown is entitled to challenge the accused’s explanation through cross-examination.
R. v. Hill, at para. 48.