If an accused chooses to testify at a criminal trial in Canada, the general rule is that the state is permitted to cross-examine the accused on his criminal record for the limited purpose of challenging his credibility (see Canada Evidence Act s. 12 and R. v. Corbett,  1 S.C.R. 670).
There are, however, strict limitations on the permissible scope of questions that a Crown may ask an accused about his criminal record:
1) “…an accused can only be cross-examined on the bare bones of his or her criminal record, the charge, the date and the punishment imposed…” - an accused cannot be cross-examined on the details of the conduct underlying each conviction (R. v. Borden,  N.S.J. No. 206 (C.A.) at para. 123)(also see Corbett at para. 48);
2) “….an accused may be cross-examined only as to “convictions” strictly construed … there can be no cross-examination where the accused was found guilty and granted a conditional discharge, conditions subsequently having been fulfilled…”(Corbett, para. 48) (see also Borden at para. 121);
3) “The Crown is not entitled to go beyond prior convictions to cross-examine an accused as to … association with disreputable individuals…”(Corbett, para. 48); and
4) “...an accused cannot be cross-examined as to whether he testified on the prior occasion when convicted in order to show that he is one who was not believed by a jury on a previous occasion…”(Corbett, para. 48).
A Corbett application - Before deciding whether to testify, an accused may try to persuade the judge, in the interests of trial fairness, to further restrict the permissible scope of the Crown's cross-examination, and in some cases, to prohibit the Crown from bringing up the record at all.